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+BASH_BUILTINS(1) General Commands Manual BASH_BUILTINS(1)
+
+
+
+NNAAMMEE
+ bash, :, ., [, alias, bg, bind, break, builtin, caller, cd, command,
+ compgen, complete, compopt, continue, declare, dirs, disown, echo, en-
+ able, eval, exec, exit, export, false, fc, fg, getopts, hash, help,
+ history, jobs, kill, let, local, logout, mapfile, popd, printf, pushd,
+ pwd, read, readonly, return, set, shift, shopt, source, suspend, test,
+ times, trap, true, type, typeset, ulimit, umask, unalias, unset, wait -
+ bash built-in commands, see bbaasshh(1)
+
+BBAASSHH BBUUIILLTTIINN CCOOMMMMAANNDDSS
+ Unless otherwise noted, each builtin command documented in this section
+ as accepting options preceded by -- accepts ---- to signify the end of the
+ options. The ::, ttrruuee, ffaallssee, and tteesstt/[[ builtins do not accept options
+ and do not treat ---- specially. The eexxiitt, llooggoouutt, rreettuurrnn, bbrreeaakk, ccoonn--
+ ttiinnuuee, lleett, and sshhiifftt builtins accept and process arguments beginning
+ with -- without requiring ----. Other builtins that accept arguments but
+ are not specified as accepting options interpret arguments beginning
+ with -- as invalid options and require ---- to prevent this interpreta-
+ tion.
+ :: [_a_r_g_u_m_e_n_t_s]
+ No effect; the command does nothing beyond expanding _a_r_g_u_m_e_n_t_s
+ and performing any specified redirections. The return status is
+ zero.
+
+ .. _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s]
+ ssoouurrccee _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s]
+ Read and execute commands from _f_i_l_e_n_a_m_e in the current shell en-
+ vironment and return the exit status of the last command exe-
+ cuted from _f_i_l_e_n_a_m_e. If _f_i_l_e_n_a_m_e does not contain a slash,
+ filenames in PPAATTHH are used to find the directory containing
+ _f_i_l_e_n_a_m_e. The file searched for in PPAATTHH need not be executable.
+ When bbaasshh is not in _p_o_s_i_x _m_o_d_e, the current directory is
+ searched if no file is found in PPAATTHH. If the ssoouurrcceeppaatthh option
+ to the sshhoopptt builtin command is turned off, the PPAATTHH is not
+ searched. If any _a_r_g_u_m_e_n_t_s are supplied, they become the posi-
+ tional parameters when _f_i_l_e_n_a_m_e is executed. Otherwise the po-
+ sitional parameters are unchanged. If the --TT option is enabled,
+ ssoouurrccee inherits any trap on DDEEBBUUGG; if it is not, any DDEEBBUUGG trap
+ string is saved and restored around the call to ssoouurrccee, and
+ ssoouurrccee unsets the DDEEBBUUGG trap while it executes. If --TT is not
+ set, and the sourced file changes the DDEEBBUUGG trap, the new value
+ is retained when ssoouurrccee completes. The return status is the
+ status of the last command exited within the script (0 if no
+ commands are executed), and false if _f_i_l_e_n_a_m_e is not found or
+ cannot be read.
+
+ aalliiaass [--pp] [_n_a_m_e[=_v_a_l_u_e] ...]
+ AAlliiaass with no arguments or with the --pp option prints the list of
+ aliases in the form aalliiaass _n_a_m_e=_v_a_l_u_e on standard output. When
+ arguments are supplied, an alias is defined for each _n_a_m_e whose
+ _v_a_l_u_e is given. A trailing space in _v_a_l_u_e causes the next word
+ to be checked for alias substitution when the alias is expanded.
+ For each _n_a_m_e in the argument list for which no _v_a_l_u_e is sup-
+ plied, the name and value of the alias is printed. AAlliiaass re-
+ turns true unless a _n_a_m_e is given for which no alias has been
+ defined.
+
+ bbgg [_j_o_b_s_p_e_c ...]
+ Resume each suspended job _j_o_b_s_p_e_c in the background, as if it
+ had been started with &&. If _j_o_b_s_p_e_c is not present, the shell's
+ notion of the _c_u_r_r_e_n_t _j_o_b is used. bbgg _j_o_b_s_p_e_c returns 0 unless
+ run when job control is disabled or, when run with job control
+ enabled, any specified _j_o_b_s_p_e_c was not found or was started
+ without job control.
+
+ bbiinndd [--mm _k_e_y_m_a_p] [--llppssvvPPSSVVXX]
+ bbiinndd [--mm _k_e_y_m_a_p] [--qq _f_u_n_c_t_i_o_n] [--uu _f_u_n_c_t_i_o_n] [--rr _k_e_y_s_e_q]
+ bbiinndd [--mm _k_e_y_m_a_p] --ff _f_i_l_e_n_a_m_e
+ bbiinndd [--mm _k_e_y_m_a_p] --xx _k_e_y_s_e_q:_s_h_e_l_l_-_c_o_m_m_a_n_d
+ bbiinndd [--mm _k_e_y_m_a_p] _k_e_y_s_e_q:_f_u_n_c_t_i_o_n_-_n_a_m_e
+ bbiinndd [--mm _k_e_y_m_a_p] _k_e_y_s_e_q:_r_e_a_d_l_i_n_e_-_c_o_m_m_a_n_d
+ Display current rreeaaddlliinnee key and function bindings, bind a key
+ sequence to a rreeaaddlliinnee function or macro, or set a rreeaaddlliinnee
+ variable. Each non-option argument is a command as it would ap-
+ pear in _._i_n_p_u_t_r_c, but each binding or command must be passed as
+ a separate argument; e.g., '"\C-x\C-r": re-read-init-file'. Op-
+ tions, if supplied, have the following meanings:
+ --mm _k_e_y_m_a_p
+ Use _k_e_y_m_a_p as the keymap to be affected by the subsequent
+ bindings. Acceptable _k_e_y_m_a_p names are _e_m_a_c_s_, _e_m_a_c_s_-_s_t_a_n_-
+ _d_a_r_d_, _e_m_a_c_s_-_m_e_t_a_, _e_m_a_c_s_-_c_t_l_x_, _v_i_, _v_i_-_m_o_v_e_, _v_i_-_c_o_m_m_a_n_d,
+ and _v_i_-_i_n_s_e_r_t. _v_i is equivalent to _v_i_-_c_o_m_m_a_n_d (_v_i_-_m_o_v_e
+ is also a synonym); _e_m_a_c_s is equivalent to _e_m_a_c_s_-_s_t_a_n_-
+ _d_a_r_d.
+ --ll List the names of all rreeaaddlliinnee functions.
+ --pp Display rreeaaddlliinnee function names and bindings in such a
+ way that they can be re-read.
+ --PP List current rreeaaddlliinnee function names and bindings.
+ --ss Display rreeaaddlliinnee key sequences bound to macros and the
+ strings they output in such a way that they can be re-
+ read.
+ --SS Display rreeaaddlliinnee key sequences bound to macros and the
+ strings they output.
+ --vv Display rreeaaddlliinnee variable names and values in such a way
+ that they can be re-read.
+ --VV List current rreeaaddlliinnee variable names and values.
+ --ff _f_i_l_e_n_a_m_e
+ Read key bindings from _f_i_l_e_n_a_m_e.
+ --qq _f_u_n_c_t_i_o_n
+ Query about which keys invoke the named _f_u_n_c_t_i_o_n.
+ --uu _f_u_n_c_t_i_o_n
+ Unbind all keys bound to the named _f_u_n_c_t_i_o_n.
+ --rr _k_e_y_s_e_q
+ Remove any current binding for _k_e_y_s_e_q.
+ --xx _k_e_y_s_e_q::_s_h_e_l_l_-_c_o_m_m_a_n_d
+ Cause _s_h_e_l_l_-_c_o_m_m_a_n_d to be executed whenever _k_e_y_s_e_q is en-
+ tered. When _s_h_e_l_l_-_c_o_m_m_a_n_d is executed, the shell sets
+ the RREEAADDLLIINNEE__LLIINNEE variable to the contents of the rreeaadd--
+ lliinnee line buffer and the RREEAADDLLIINNEE__PPOOIINNTT and RREEAADDLLIINNEE__MMAARRKK
+ variables to the current location of the insertion point
+ and the saved insertion point (the mark), respectively.
+ If the executed command changes the value of any of RREEAADD--
+ LLIINNEE__LLIINNEE, RREEAADDLLIINNEE__PPOOIINNTT, or RREEAADDLLIINNEE__MMAARRKK, those new
+ values will be reflected in the editing state.
+ --XX List all key sequences bound to shell commands and the
+ associated commands in a format that can be reused as in-
+ put.
+
+ The return value is 0 unless an unrecognized option is given or
+ an error occurred.
+
+ bbrreeaakk [_n]
+ Exit from within a ffoorr, wwhhiillee, uunnttiill, or sseelleecctt loop. If _n is
+ specified, break _n levels. _n must be >= 1. If _n is greater
+ than the number of enclosing loops, all enclosing loops are ex-
+ ited. The return value is 0 unless _n is not greater than or
+ equal to 1.
+
+ bbuuiillttiinn _s_h_e_l_l_-_b_u_i_l_t_i_n [_a_r_g_u_m_e_n_t_s]
+ Execute the specified shell builtin, passing it _a_r_g_u_m_e_n_t_s, and
+ return its exit status. This is useful when defining a function
+ whose name is the same as a shell builtin, retaining the func-
+ tionality of the builtin within the function. The ccdd builtin is
+ commonly redefined this way. The return status is false if
+ _s_h_e_l_l_-_b_u_i_l_t_i_n is not a shell builtin command.
+
+ ccaalllleerr [_e_x_p_r]
+ Returns the context of any active subroutine call (a shell func-
+ tion or a script executed with the .. or ssoouurrccee builtins). With-
+ out _e_x_p_r, ccaalllleerr displays the line number and source filename of
+ the current subroutine call. If a non-negative integer is sup-
+ plied as _e_x_p_r, ccaalllleerr displays the line number, subroutine name,
+ and source file corresponding to that position in the current
+ execution call stack. This extra information may be used, for
+ example, to print a stack trace. The current frame is frame 0.
+ The return value is 0 unless the shell is not executing a sub-
+ routine call or _e_x_p_r does not correspond to a valid position in
+ the call stack.
+
+ ccdd [--LL|[--PP [--ee]] [-@]] [_d_i_r]
+ Change the current directory to _d_i_r. if _d_i_r is not supplied,
+ the value of the HHOOMMEE shell variable is the default. Any addi-
+ tional arguments following _d_i_r are ignored. The variable CCDDPPAATTHH
+ defines the search path for the directory containing _d_i_r: each
+ directory name in CCDDPPAATTHH is searched for _d_i_r. Alternative di-
+ rectory names in CCDDPPAATTHH are separated by a colon (:). A null
+ directory name in CCDDPPAATTHH is the same as the current directory,
+ i.e., ``..''. If _d_i_r begins with a slash (/), then CCDDPPAATTHH is not
+ used. The --PP option causes ccdd to use the physical directory
+ structure by resolving symbolic links while traversing _d_i_r and
+ before processing instances of _._. in _d_i_r (see also the --PP option
+ to the sseett builtin command); the --LL option forces symbolic links
+ to be followed by resolving the link after processing instances
+ of _._. in _d_i_r. If _._. appears in _d_i_r, it is processed by removing
+ the immediately previous pathname component from _d_i_r, back to a
+ slash or the beginning of _d_i_r. If the --ee option is supplied
+ with --PP, and the current working directory cannot be success-
+ fully determined after a successful directory change, ccdd will
+ return an unsuccessful status. On systems that support it, the
+ --@@ option presents the extended attributes associated with a
+ file as a directory. An argument of -- is converted to $$OOLLDDPPWWDD
+ before the directory change is attempted. If a non-empty direc-
+ tory name from CCDDPPAATTHH is used, or if -- is the first argument,
+ and the directory change is successful, the absolute pathname of
+ the new working directory is written to the standard output.
+ The return value is true if the directory was successfully
+ changed; false otherwise.
+
+ ccoommmmaanndd [--ppVVvv] _c_o_m_m_a_n_d [_a_r_g ...]
+ Run _c_o_m_m_a_n_d with _a_r_g_s suppressing the normal shell function
+ lookup. Only builtin commands or commands found in the PPAATTHH are
+ executed. If the --pp option is given, the search for _c_o_m_m_a_n_d is
+ performed using a default value for PPAATTHH that is guaranteed to
+ find all of the standard utilities. If either the --VV or --vv op-
+ tion is supplied, a description of _c_o_m_m_a_n_d is printed. The --vv
+ option causes a single word indicating the command or filename
+ used to invoke _c_o_m_m_a_n_d to be displayed; the --VV option produces a
+ more verbose description. If the --VV or --vv option is supplied,
+ the exit status is 0 if _c_o_m_m_a_n_d was found, and 1 if not. If
+ neither option is supplied and an error occurred or _c_o_m_m_a_n_d can-
+ not be found, the exit status is 127. Otherwise, the exit sta-
+ tus of the ccoommmmaanndd builtin is the exit status of _c_o_m_m_a_n_d.
+
+ ccoommppggeenn [_o_p_t_i_o_n] [_w_o_r_d]
+ Generate possible completion matches for _w_o_r_d according to the
+ _o_p_t_i_o_ns, which may be any option accepted by the ccoommpplleettee
+ builtin with the exception of --pp and --rr, and write the matches
+ to the standard output. When using the --FF or --CC options, the
+ various shell variables set by the programmable completion fa-
+ cilities, while available, will not have useful values.
+
+ The matches will be generated in the same way as if the program-
+ mable completion code had generated them directly from a comple-
+ tion specification with the same flags. If _w_o_r_d is specified,
+ only those completions matching _w_o_r_d will be displayed.
+
+ The return value is true unless an invalid option is supplied,
+ or no matches were generated.
+
+ ccoommpplleettee [--aabbccddeeffggjjkkssuuvv] [--oo _c_o_m_p_-_o_p_t_i_o_n] [--DDEEII] [--AA _a_c_t_i_o_n] [--GG _g_l_o_b_-
+ _p_a_t] [--WW _w_o_r_d_l_i_s_t]
+ [--FF _f_u_n_c_t_i_o_n] [--CC _c_o_m_m_a_n_d] [--XX _f_i_l_t_e_r_p_a_t] [--PP _p_r_e_f_i_x] [--SS _s_u_f_-
+ _f_i_x] _n_a_m_e [_n_a_m_e _._._.]
+ ccoommpplleettee --pprr [--DDEEII] [_n_a_m_e ...]
+ Specify how arguments to each _n_a_m_e should be completed. If the
+ --pp option is supplied, or if no options are supplied, existing
+ completion specifications are printed in a way that allows them
+ to be reused as input. The --rr option removes a completion spec-
+ ification for each _n_a_m_e, or, if no _n_a_m_es are supplied, all com-
+ pletion specifications. The --DD option indicates that other sup-
+ plied options and actions should apply to the ``default'' com-
+ mand completion; that is, completion attempted on a command for
+ which no completion has previously been defined. The --EE option
+ indicates that other supplied options and actions should apply
+ to ``empty'' command completion; that is, completion attempted
+ on a blank line. The --II option indicates that other supplied
+ options and actions should apply to completion on the initial
+ non-assignment word on the line, or after a command delimiter
+ such as ;; or ||, which is usually command name completion. If
+ multiple options are supplied, the --DD option takes precedence
+ over --EE, and both take precedence over --II. If any of --DD, --EE, or
+ --II are supplied, any other _n_a_m_e arguments are ignored; these
+ completions only apply to the case specified by the option.
+
+ The process of applying these completion specifications when
+ word completion is attempted is described above under PPrrooggrraamm--
+ mmaabbllee CCoommpplleettiioonn.
+
+ Other options, if specified, have the following meanings. The
+ arguments to the --GG, --WW, and --XX options (and, if necessary, the
+ --PP and --SS options) should be quoted to protect them from expan-
+ sion before the ccoommpplleettee builtin is invoked.
+ --oo _c_o_m_p_-_o_p_t_i_o_n
+ The _c_o_m_p_-_o_p_t_i_o_n controls several aspects of the comp-
+ spec's behavior beyond the simple generation of comple-
+ tions. _c_o_m_p_-_o_p_t_i_o_n may be one of:
+ bbaasshhddeeffaauulltt
+ Perform the rest of the default bbaasshh completions
+ if the compspec generates no matches.
+ ddeeffaauulltt Use readline's default filename completion if
+ the compspec generates no matches.
+ ddiirrnnaammeess
+ Perform directory name completion if the comp-
+ spec generates no matches.
+ ffiilleennaammeess
+ Tell readline that the compspec generates file-
+ names, so it can perform any filename-specific
+ processing (like adding a slash to directory
+ names, quoting special characters, or suppress-
+ ing trailing spaces). Intended to be used with
+ shell functions.
+ nnooqquuoottee Tell readline not to quote the completed words
+ if they are filenames (quoting filenames is the
+ default).
+ nnoossoorrtt Tell readline not to sort the list of possible
+ completions alphabetically.
+ nnoossppaaccee Tell readline not to append a space (the de-
+ fault) to words completed at the end of the
+ line.
+ pplluussddiirrss
+ After any matches defined by the compspec are
+ generated, directory name completion is at-
+ tempted and any matches are added to the results
+ of the other actions.
+ --AA _a_c_t_i_o_n
+ The _a_c_t_i_o_n may be one of the following to generate a
+ list of possible completions:
+ aalliiaass Alias names. May also be specified as --aa.
+ aarrrraayyvvaarr
+ Array variable names.
+ bbiinnddiinngg RReeaaddlliinnee key binding names.
+ bbuuiillttiinn Names of shell builtin commands. May also be
+ specified as --bb.
+ ccoommmmaanndd Command names. May also be specified as --cc.
+ ddiirreeccttoorryy
+ Directory names. May also be specified as --dd.
+ ddiissaabblleedd
+ Names of disabled shell builtins.
+ eennaabblleedd Names of enabled shell builtins.
+ eexxppoorrtt Names of exported shell variables. May also be
+ specified as --ee.
+ ffiillee File names. May also be specified as --ff.
+ ffuunnccttiioonn
+ Names of shell functions.
+ ggrroouupp Group names. May also be specified as --gg.
+ hheellppttooppiicc
+ Help topics as accepted by the hheellpp builtin.
+ hhoossttnnaammee
+ Hostnames, as taken from the file specified by
+ the HHOOSSTTFFIILLEE shell variable.
+ jjoobb Job names, if job control is active. May also
+ be specified as --jj.
+ kkeeyywwoorrdd Shell reserved words. May also be specified as
+ --kk.
+ rruunnnniinngg Names of running jobs, if job control is active.
+ sseerrvviiccee Service names. May also be specified as --ss.
+ sseettoopptt Valid arguments for the --oo option to the sseett
+ builtin.
+ sshhoopptt Shell option names as accepted by the sshhoopptt
+ builtin.
+ ssiiggnnaall Signal names.
+ ssttooppppeedd Names of stopped jobs, if job control is active.
+ uusseerr User names. May also be specified as --uu.
+ vvaarriiaabbllee
+ Names of all shell variables. May also be spec-
+ ified as --vv.
+ --CC _c_o_m_m_a_n_d
+ _c_o_m_m_a_n_d is executed in a subshell environment, and its
+ output is used as the possible completions.
+ --FF _f_u_n_c_t_i_o_n
+ The shell function _f_u_n_c_t_i_o_n is executed in the current
+ shell environment. When the function is executed, the
+ first argument ($$11) is the name of the command whose ar-
+ guments are being completed, the second argument ($$22) is
+ the word being completed, and the third argument ($$33) is
+ the word preceding the word being completed on the cur-
+ rent command line. When it finishes, the possible com-
+ pletions are retrieved from the value of the CCOOMMPPRREEPPLLYY
+ array variable.
+ --GG _g_l_o_b_p_a_t
+ The pathname expansion pattern _g_l_o_b_p_a_t is expanded to
+ generate the possible completions.
+ --PP _p_r_e_f_i_x
+ _p_r_e_f_i_x is added at the beginning of each possible com-
+ pletion after all other options have been applied.
+ --SS _s_u_f_f_i_x
+ _s_u_f_f_i_x is appended to each possible completion after all
+ other options have been applied.
+ --WW _w_o_r_d_l_i_s_t
+ The _w_o_r_d_l_i_s_t is split using the characters in the IIFFSS
+ special variable as delimiters, and each resultant word
+ is expanded. Shell quoting is honored within _w_o_r_d_l_i_s_t,
+ in order to provide a mechanism for the words to contain
+ shell metacharacters or characters in the value of IIFFSS.
+ The possible completions are the members of the resul-
+ tant list which match the word being completed.
+ --XX _f_i_l_t_e_r_p_a_t
+ _f_i_l_t_e_r_p_a_t is a pattern as used for pathname expansion.
+ It is applied to the list of possible completions gener-
+ ated by the preceding options and arguments, and each
+ completion matching _f_i_l_t_e_r_p_a_t is removed from the list.
+ A leading !! in _f_i_l_t_e_r_p_a_t negates the pattern; in this
+ case, any completion not matching _f_i_l_t_e_r_p_a_t is removed.
+
+ The return value is true unless an invalid option is supplied,
+ an option other than --pp or --rr is supplied without a _n_a_m_e argu-
+ ment, an attempt is made to remove a completion specification
+ for a _n_a_m_e for which no specification exists, or an error occurs
+ adding a completion specification.
+
+ ccoommppoopptt [--oo _o_p_t_i_o_n] [--DDEEII] [++oo _o_p_t_i_o_n] [_n_a_m_e]
+ Modify completion options for each _n_a_m_e according to the _o_p_-
+ _t_i_o_ns, or for the currently-executing completion if no _n_a_m_es are
+ supplied. If no _o_p_t_i_o_ns are given, display the completion op-
+ tions for each _n_a_m_e or the current completion. The possible
+ values of _o_p_t_i_o_n are those valid for the ccoommpplleettee builtin de-
+ scribed above. The --DD option indicates that other supplied op-
+ tions should apply to the ``default'' command completion; that
+ is, completion attempted on a command for which no completion
+ has previously been defined. The --EE option indicates that other
+ supplied options should apply to ``empty'' command completion;
+ that is, completion attempted on a blank line. The --II option
+ indicates that other supplied options should apply to completion
+ on the initial non-assignment word on the line, or after a com-
+ mand delimiter such as ;; or ||, which is usually command name
+ completion.
+
+ The return value is true unless an invalid option is supplied,
+ an attempt is made to modify the options for a _n_a_m_e for which no
+ completion specification exists, or an output error occurs.
+
+ ccoonnttiinnuuee [_n]
+ Resume the next iteration of the enclosing ffoorr, wwhhiillee, uunnttiill, or
+ sseelleecctt loop. If _n is specified, resume at the _nth enclosing
+ loop. _n must be >= 1. If _n is greater than the number of en-
+ closing loops, the last enclosing loop (the ``top-level'' loop)
+ is resumed. The return value is 0 unless _n is not greater than
+ or equal to 1.
+
+ ddeeccllaarree [--aaAAffFFggiiIIllnnrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...]
+ ttyyppeesseett [--aaAAffFFggiiIIllnnrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...]
+ Declare variables and/or give them attributes. If no _n_a_m_es are
+ given then display the values of variables. The --pp option will
+ display the attributes and values of each _n_a_m_e. When --pp is used
+ with _n_a_m_e arguments, additional options, other than --ff and --FF,
+ are ignored. When --pp is supplied without _n_a_m_e arguments, it
+ will display the attributes and values of all variables having
+ the attributes specified by the additional options. If no other
+ options are supplied with --pp, ddeeccllaarree will display the at-
+ tributes and values of all shell variables. The --ff option will
+ restrict the display to shell functions. The --FF option inhibits
+ the display of function definitions; only the function name and
+ attributes are printed. If the eexxttddeebbuugg shell option is enabled
+ using sshhoopptt, the source file name and line number where each
+ _n_a_m_e is defined are displayed as well. The --FF option implies
+ --ff. The --gg option forces variables to be created or modified at
+ the global scope, even when ddeeccllaarree is executed in a shell func-
+ tion. It is ignored in all other cases. The --II option causes
+ local variables to inherit the attributes (except the _n_a_m_e_r_e_f
+ attribute) and value of any existing variable with the same _n_a_m_e
+ at a surrounding scope. If there is no existing variable, the
+ local variable is initially unset. The following options can be
+ used to restrict output to variables with the specified attri-
+ bute or to give variables attributes:
+ --aa Each _n_a_m_e is an indexed array variable (see AArrrraayyss
+ above).
+ --AA Each _n_a_m_e is an associative array variable (see AArrrraayyss
+ above).
+ --ff Use function names only.
+ --ii The variable is treated as an integer; arithmetic evalua-
+ tion (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN above) is performed when
+ the variable is assigned a value.
+ --ll When the variable is assigned a value, all upper-case
+ characters are converted to lower-case. The upper-case
+ attribute is disabled.
+ --nn Give each _n_a_m_e the _n_a_m_e_r_e_f attribute, making it a name
+ reference to another variable. That other variable is
+ defined by the value of _n_a_m_e. All references, assign-
+ ments, and attribute modifications to _n_a_m_e, except those
+ using or changing the --nn attribute itself, are performed
+ on the variable referenced by _n_a_m_e's value. The nameref
+ attribute cannot be applied to array variables.
+ --rr Make _n_a_m_es readonly. These names cannot then be assigned
+ values by subsequent assignment statements or unset.
+ --tt Give each _n_a_m_e the _t_r_a_c_e attribute. Traced functions in-
+ herit the DDEEBBUUGG and RREETTUURRNN traps from the calling shell.
+ The trace attribute has no special meaning for variables.
+ --uu When the variable is assigned a value, all lower-case
+ characters are converted to upper-case. The lower-case
+ attribute is disabled.
+ --xx Mark _n_a_m_es for export to subsequent commands via the en-
+ vironment.
+
+ Using `+' instead of `-' turns off the attribute instead, with
+ the exceptions that ++aa and ++AA may not be used to destroy array
+ variables and ++rr will not remove the readonly attribute. When
+ used in a function, ddeeccllaarree and ttyyppeesseett make each _n_a_m_e local, as
+ with the llooccaall command, unless the --gg option is supplied. If a
+ variable name is followed by =_v_a_l_u_e, the value of the variable
+ is set to _v_a_l_u_e. When using --aa or --AA and the compound assign-
+ ment syntax to create array variables, additional attributes do
+ not take effect until subsequent assignments. The return value
+ is 0 unless an invalid option is encountered, an attempt is made
+ to define a function using ``-f foo=bar'', an attempt is made to
+ assign a value to a readonly variable, an attempt is made to as-
+ sign a value to an array variable without using the compound as-
+ signment syntax (see AArrrraayyss above), one of the _n_a_m_e_s is not a
+ valid shell variable name, an attempt is made to turn off read-
+ only status for a readonly variable, an attempt is made to turn
+ off array status for an array variable, or an attempt is made to
+ display a non-existent function with --ff.
+
+ ddiirrss [[--ccllppvv]] [[++_n]] [[--_n]]
+ Without options, displays the list of currently remembered di-
+ rectories. The default display is on a single line with direc-
+ tory names separated by spaces. Directories are added to the
+ list with the ppuusshhdd command; the ppooppdd command removes entries
+ from the list. The current directory is always the first direc-
+ tory in the stack.
+ --cc Clears the directory stack by deleting all of the en-
+ tries.
+ --ll Produces a listing using full pathnames; the default
+ listing format uses a tilde to denote the home directory.
+ --pp Print the directory stack with one entry per line.
+ --vv Print the directory stack with one entry per line, pre-
+ fixing each entry with its index in the stack.
+ ++_n Displays the _nth entry counting from the left of the list
+ shown by ddiirrss when invoked without options, starting with
+ zero.
+ --_n Displays the _nth entry counting from the right of the
+ list shown by ddiirrss when invoked without options, starting
+ with zero.
+
+ The return value is 0 unless an invalid option is supplied or _n
+ indexes beyond the end of the directory stack.
+
+ ddiissoowwnn [--aarr] [--hh] [_j_o_b_s_p_e_c ... | _p_i_d ... ]
+ Without options, remove each _j_o_b_s_p_e_c from the table of active
+ jobs. If _j_o_b_s_p_e_c is not present, and neither the --aa nor the --rr
+ option is supplied, the _c_u_r_r_e_n_t _j_o_b is used. If the --hh option
+ is given, each _j_o_b_s_p_e_c is not removed from the table, but is
+ marked so that SSIIGGHHUUPP is not sent to the job if the shell re-
+ ceives a SSIIGGHHUUPP. If no _j_o_b_s_p_e_c is supplied, the --aa option means
+ to remove or mark all jobs; the --rr option without a _j_o_b_s_p_e_c ar-
+ gument restricts operation to running jobs. The return value is
+ 0 unless a _j_o_b_s_p_e_c does not specify a valid job.
+
+ eecchhoo [--nneeEE] [_a_r_g ...]
+ Output the _a_r_gs, separated by spaces, followed by a newline.
+ The return status is 0 unless a write error occurs. If --nn is
+ specified, the trailing newline is suppressed. If the --ee option
+ is given, interpretation of the following backslash-escaped
+ characters is enabled. The --EE option disables the interpreta-
+ tion of these escape characters, even on systems where they are
+ interpreted by default. The xxppgg__eecchhoo shell option may be used
+ to dynamically determine whether or not eecchhoo expands these es-
+ cape characters by default. eecchhoo does not interpret ---- to mean
+ the end of options. eecchhoo interprets the following escape se-
+ quences:
+ \\aa alert (bell)
+ \\bb backspace
+ \\cc suppress further output
+ \\ee
+ \\EE an escape character
+ \\ff form feed
+ \\nn new line
+ \\rr carriage return
+ \\tt horizontal tab
+ \\vv vertical tab
+ \\\\ backslash
+ \\00_n_n_n the eight-bit character whose value is the octal value
+ _n_n_n (zero to three octal digits)
+ \\xx_H_H the eight-bit character whose value is the hexadecimal
+ value _H_H (one or two hex digits)
+ \\uu_H_H_H_H the Unicode (ISO/IEC 10646) character whose value is the
+ hexadecimal value _H_H_H_H (one to four hex digits)
+ \\UU_H_H_H_H_H_H_H_H
+ the Unicode (ISO/IEC 10646) character whose value is the
+ hexadecimal value _H_H_H_H_H_H_H_H (one to eight hex digits)
+
+ eennaabbllee [--aa] [--ddnnppss] [--ff _f_i_l_e_n_a_m_e] [_n_a_m_e ...]
+ Enable and disable builtin shell commands. Disabling a builtin
+ allows a disk command which has the same name as a shell builtin
+ to be executed without specifying a full pathname, even though
+ the shell normally searches for builtins before disk commands.
+ If --nn is used, each _n_a_m_e is disabled; otherwise, _n_a_m_e_s are en-
+ abled. For example, to use the tteesstt binary found via the PPAATTHH
+ instead of the shell builtin version, run ``enable -n test''.
+ The --ff option means to load the new builtin command _n_a_m_e from
+ shared object _f_i_l_e_n_a_m_e, on systems that support dynamic loading.
+ The --dd option will delete a builtin previously loaded with --ff.
+ If no _n_a_m_e arguments are given, or if the --pp option is supplied,
+ a list of shell builtins is printed. With no other option argu-
+ ments, the list consists of all enabled shell builtins. If --nn
+ is supplied, only disabled builtins are printed. If --aa is sup-
+ plied, the list printed includes all builtins, with an indica-
+ tion of whether or not each is enabled. If --ss is supplied, the
+ output is restricted to the POSIX _s_p_e_c_i_a_l builtins. The return
+ value is 0 unless a _n_a_m_e is not a shell builtin or there is an
+ error loading a new builtin from a shared object.
+
+ eevvaall [_a_r_g ...]
+ The _a_r_gs are read and concatenated together into a single com-
+ mand. This command is then read and executed by the shell, and
+ its exit status is returned as the value of eevvaall. If there are
+ no _a_r_g_s, or only null arguments, eevvaall returns 0.
+
+ eexxeecc [--ccll] [--aa _n_a_m_e] [_c_o_m_m_a_n_d [_a_r_g_u_m_e_n_t_s]]
+ If _c_o_m_m_a_n_d is specified, it replaces the shell. No new process
+ is created. The _a_r_g_u_m_e_n_t_s become the arguments to _c_o_m_m_a_n_d. If
+ the --ll option is supplied, the shell places a dash at the begin-
+ ning of the zeroth argument passed to _c_o_m_m_a_n_d. This is what _l_o_-
+ _g_i_n(1) does. The --cc option causes _c_o_m_m_a_n_d to be executed with
+ an empty environment. If --aa is supplied, the shell passes _n_a_m_e
+ as the zeroth argument to the executed command. If _c_o_m_m_a_n_d can-
+ not be executed for some reason, a non-interactive shell exits,
+ unless the eexxeeccffaaiill shell option is enabled. In that case, it
+ returns failure. An interactive shell returns failure if the
+ file cannot be executed. A subshell exits unconditionally if
+ eexxeecc fails. If _c_o_m_m_a_n_d is not specified, any redirections take
+ effect in the current shell, and the return status is 0. If
+ there is a redirection error, the return status is 1.
+
+ eexxiitt [_n]
+ Cause the shell to exit with a status of _n. If _n is omitted,
+ the exit status is that of the last command executed. A trap on
+ EEXXIITT is executed before the shell terminates.
+
+ eexxppoorrtt [--ffnn] [_n_a_m_e[=_w_o_r_d]] ...
+ eexxppoorrtt --pp
+ The supplied _n_a_m_e_s are marked for automatic export to the envi-
+ ronment of subsequently executed commands. If the --ff option is
+ given, the _n_a_m_e_s refer to functions. If no _n_a_m_e_s are given, or
+ if the --pp option is supplied, a list of names of all exported
+ variables is printed. The --nn option causes the export property
+ to be removed from each _n_a_m_e. If a variable name is followed by
+ =_w_o_r_d, the value of the variable is set to _w_o_r_d. eexxppoorrtt returns
+ an exit status of 0 unless an invalid option is encountered, one
+ of the _n_a_m_e_s is not a valid shell variable name, or --ff is sup-
+ plied with a _n_a_m_e that is not a function.
+
+ ffcc [--ee _e_n_a_m_e] [--llnnrr] [_f_i_r_s_t] [_l_a_s_t]
+ ffcc --ss [_p_a_t=_r_e_p] [_c_m_d]
+ The first form selects a range of commands from _f_i_r_s_t to _l_a_s_t
+ from the history list and displays or edits and re-executes
+ them. _F_i_r_s_t and _l_a_s_t may be specified as a string (to locate
+ the last command beginning with that string) or as a number (an
+ index into the history list, where a negative number is used as
+ an offset from the current command number). When listing, a
+ _f_i_r_s_t or _l_a_s_t of 0 is equivalent to -1 and -0 is equivalent to
+ the current command (usually the ffcc command); otherwise 0 is
+ equivalent to -1 and -0 is invalid. If _l_a_s_t is not specified,
+ it is set to the current command for listing (so that ``fc -l
+ -10'' prints the last 10 commands) and to _f_i_r_s_t otherwise. If
+ _f_i_r_s_t is not specified, it is set to the previous command for
+ editing and -16 for listing.
+
+ The --nn option suppresses the command numbers when listing. The
+ --rr option reverses the order of the commands. If the --ll option
+ is given, the commands are listed on standard output. Other-
+ wise, the editor given by _e_n_a_m_e is invoked on a file containing
+ those commands. If _e_n_a_m_e is not given, the value of the FFCCEEDDIITT
+ variable is used, and the value of EEDDIITTOORR if FFCCEEDDIITT is not set.
+ If neither variable is set, _v_i is used. When editing is com-
+ plete, the edited commands are echoed and executed.
+
+ In the second form, _c_o_m_m_a_n_d is re-executed after each instance
+ of _p_a_t is replaced by _r_e_p. _C_o_m_m_a_n_d is interpreted the same as
+ _f_i_r_s_t above. A useful alias to use with this is ``r="fc -s"'',
+ so that typing ``r cc'' runs the last command beginning with
+ ``cc'' and typing ``r'' re-executes the last command.
+
+ If the first form is used, the return value is 0 unless an in-
+ valid option is encountered or _f_i_r_s_t or _l_a_s_t specify history
+ lines out of range. If the --ee option is supplied, the return
+ value is the value of the last command executed or failure if an
+ error occurs with the temporary file of commands. If the second
+ form is used, the return status is that of the command re-exe-
+ cuted, unless _c_m_d does not specify a valid history line, in
+ which case ffcc returns failure.
+
+ ffgg [_j_o_b_s_p_e_c]
+ Resume _j_o_b_s_p_e_c in the foreground, and make it the current job.
+ If _j_o_b_s_p_e_c is not present, the shell's notion of the _c_u_r_r_e_n_t _j_o_b
+ is used. The return value is that of the command placed into
+ the foreground, or failure if run when job control is disabled
+ or, when run with job control enabled, if _j_o_b_s_p_e_c does not spec-
+ ify a valid job or _j_o_b_s_p_e_c specifies a job that was started
+ without job control.
+
+ ggeettooppttss _o_p_t_s_t_r_i_n_g _n_a_m_e [_a_r_g _._._.]
+ ggeettooppttss is used by shell procedures to parse positional parame-
+ ters. _o_p_t_s_t_r_i_n_g contains the option characters to be recog-
+ nized; if a character is followed by a colon, the option is ex-
+ pected to have an argument, which should be separated from it by
+ white space. The colon and question mark characters may not be
+ used as option characters. Each time it is invoked, ggeettooppttss
+ places the next option in the shell variable _n_a_m_e, initializing
+ _n_a_m_e if it does not exist, and the index of the next argument to
+ be processed into the variable OOPPTTIINNDD. OOPPTTIINNDD is initialized to
+ 1 each time the shell or a shell script is invoked. When an op-
+ tion requires an argument, ggeettooppttss places that argument into the
+ variable OOPPTTAARRGG. The shell does not reset OOPPTTIINNDD automatically;
+ it must be manually reset between multiple calls to ggeettooppttss
+ within the same shell invocation if a new set of parameters is
+ to be used.
+
+ When the end of options is encountered, ggeettooppttss exits with a re-
+ turn value greater than zero. OOPPTTIINNDD is set to the index of the
+ first non-option argument, and _n_a_m_e is set to ?.
+
+ ggeettooppttss normally parses the positional parameters, but if more
+ arguments are supplied as _a_r_g values, ggeettooppttss parses those in-
+ stead.
+
+ ggeettooppttss can report errors in two ways. If the first character
+ of _o_p_t_s_t_r_i_n_g is a colon, _s_i_l_e_n_t error reporting is used. In
+ normal operation, diagnostic messages are printed when invalid
+ options or missing option arguments are encountered. If the
+ variable OOPPTTEERRRR is set to 0, no error messages will be dis-
+ played, even if the first character of _o_p_t_s_t_r_i_n_g is not a colon.
+
+ If an invalid option is seen, ggeettooppttss places ? into _n_a_m_e and, if
+ not silent, prints an error message and unsets OOPPTTAARRGG. If
+ ggeettooppttss is silent, the option character found is placed in OOPP--
+ TTAARRGG and no diagnostic message is printed.
+
+ If a required argument is not found, and ggeettooppttss is not silent,
+ a question mark (??) is placed in _n_a_m_e, OOPPTTAARRGG is unset, and a
+ diagnostic message is printed. If ggeettooppttss is silent, then a
+ colon (::) is placed in _n_a_m_e and OOPPTTAARRGG is set to the option
+ character found.
+
+ ggeettooppttss returns true if an option, specified or unspecified, is
+ found. It returns false if the end of options is encountered or
+ an error occurs.
+
+ hhaasshh [--llrr] [--pp _f_i_l_e_n_a_m_e] [--ddtt] [_n_a_m_e]
+ Each time hhaasshh is invoked, the full pathname of the command _n_a_m_e
+ is determined by searching the directories in $$PPAATTHH and remem-
+ bered. Any previously-remembered pathname is discarded. If the
+ --pp option is supplied, no path search is performed, and _f_i_l_e_n_a_m_e
+ is used as the full filename of the command. The --rr option
+ causes the shell to forget all remembered locations. The --dd op-
+ tion causes the shell to forget the remembered location of each
+ _n_a_m_e. If the --tt option is supplied, the full pathname to which
+ each _n_a_m_e corresponds is printed. If multiple _n_a_m_e arguments
+ are supplied with --tt, the _n_a_m_e is printed before the hashed full
+ pathname. The --ll option causes output to be displayed in a for-
+ mat that may be reused as input. If no arguments are given, or
+ if only --ll is supplied, information about remembered commands is
+ printed. The return status is true unless a _n_a_m_e is not found
+ or an invalid option is supplied.
+
+ hheellpp [--ddmmss] [_p_a_t_t_e_r_n]
+ Display helpful information about builtin commands. If _p_a_t_t_e_r_n
+ is specified, hheellpp gives detailed help on all commands matching
+ _p_a_t_t_e_r_n; otherwise help for all the builtins and shell control
+ structures is printed.
+ --dd Display a short description of each _p_a_t_t_e_r_n
+ --mm Display the description of each _p_a_t_t_e_r_n in a manpage-like
+ format
+ --ss Display only a short usage synopsis for each _p_a_t_t_e_r_n
+
+ The return status is 0 unless no command matches _p_a_t_t_e_r_n.
+
+ hhiissttoorryy [[_n]]
+ hhiissttoorryy --cc
+ hhiissttoorryy --dd _o_f_f_s_e_t
+ hhiissttoorryy --dd _s_t_a_r_t-_e_n_d
+ hhiissttoorryy --aannrrww [_f_i_l_e_n_a_m_e]
+ hhiissttoorryy --pp _a_r_g [_a_r_g _._._.]
+ hhiissttoorryy --ss _a_r_g [_a_r_g _._._.]
+ With no options, display the command history list with line num-
+ bers. Lines listed with a ** have been modified. An argument of
+ _n lists only the last _n lines. If the shell variable HHIISSTTTTIIMMEE--
+ FFOORRMMAATT is set and not null, it is used as a format string for
+ _s_t_r_f_t_i_m_e(3) to display the time stamp associated with each dis-
+ played history entry. No intervening blank is printed between
+ the formatted time stamp and the history line. If _f_i_l_e_n_a_m_e is
+ supplied, it is used as the name of the history file; if not,
+ the value of HHIISSTTFFIILLEE is used. Options, if supplied, have the
+ following meanings:
+ --cc Clear the history list by deleting all the entries.
+ --dd _o_f_f_s_e_t
+ Delete the history entry at position _o_f_f_s_e_t. If _o_f_f_s_e_t
+ is negative, it is interpreted as relative to one greater
+ than the last history position, so negative indices count
+ back from the end of the history, and an index of -1
+ refers to the current hhiissttoorryy --dd command.
+ --dd _s_t_a_r_t-_e_n_d
+ Delete the history entries between positions _s_t_a_r_t and
+ _e_n_d, inclusive. Positive and negative values for _s_t_a_r_t
+ and _e_n_d are interpreted as described above.
+ --aa Append the ``new'' history lines to the history file.
+ These are history lines entered since the beginning of
+ the current bbaasshh session, but not already appended to the
+ history file.
+ --nn Read the history lines not already read from the history
+ file into the current history list. These are lines ap-
+ pended to the history file since the beginning of the
+ current bbaasshh session.
+ --rr Read the contents of the history file and append them to
+ the current history list.
+ --ww Write the current history list to the history file, over-
+ writing the history file's contents.
+ --pp Perform history substitution on the following _a_r_g_s and
+ display the result on the standard output. Does not
+ store the results in the history list. Each _a_r_g must be
+ quoted to disable normal history expansion.
+ --ss Store the _a_r_g_s in the history list as a single entry.
+ The last command in the history list is removed before
+ the _a_r_g_s are added.
+
+ If the HHIISSTTTTIIMMEEFFOORRMMAATT variable is set, the time stamp informa-
+ tion associated with each history entry is written to the his-
+ tory file, marked with the history comment character. When the
+ history file is read, lines beginning with the history comment
+ character followed immediately by a digit are interpreted as
+ timestamps for the following history entry. The return value is
+ 0 unless an invalid option is encountered, an error occurs while
+ reading or writing the history file, an invalid _o_f_f_s_e_t is sup-
+ plied as an argument to --dd, or the history expansion supplied as
+ an argument to --pp fails.
+
+ jjoobbss [--llnnpprrss] [ _j_o_b_s_p_e_c ... ]
+ jjoobbss --xx _c_o_m_m_a_n_d [ _a_r_g_s ... ]
+ The first form lists the active jobs. The options have the fol-
+ lowing meanings:
+ --ll List process IDs in addition to the normal information.
+ --nn Display information only about jobs that have changed
+ status since the user was last notified of their status.
+ --pp List only the process ID of the job's process group
+ leader.
+ --rr Display only running jobs.
+ --ss Display only stopped jobs.
+
+ If _j_o_b_s_p_e_c is given, output is restricted to information about
+ that job. The return status is 0 unless an invalid option is
+ encountered or an invalid _j_o_b_s_p_e_c is supplied.
+
+ If the --xx option is supplied, jjoobbss replaces any _j_o_b_s_p_e_c found in
+ _c_o_m_m_a_n_d or _a_r_g_s with the corresponding process group ID, and ex-
+ ecutes _c_o_m_m_a_n_d passing it _a_r_g_s, returning its exit status.
+
+ kkiillll [--ss _s_i_g_s_p_e_c | --nn _s_i_g_n_u_m | --_s_i_g_s_p_e_c] [_p_i_d | _j_o_b_s_p_e_c] ...
+ kkiillll --ll|--LL [_s_i_g_s_p_e_c | _e_x_i_t___s_t_a_t_u_s]
+ Send the signal named by _s_i_g_s_p_e_c or _s_i_g_n_u_m to the processes
+ named by _p_i_d or _j_o_b_s_p_e_c. _s_i_g_s_p_e_c is either a case-insensitive
+ signal name such as SSIIGGKKIILLLL (with or without the SSIIGG prefix) or
+ a signal number; _s_i_g_n_u_m is a signal number. If _s_i_g_s_p_e_c is not
+ present, then SSIIGGTTEERRMM is assumed. An argument of --ll lists the
+ signal names. If any arguments are supplied when --ll is given,
+ the names of the signals corresponding to the arguments are
+ listed, and the return status is 0. The _e_x_i_t___s_t_a_t_u_s argument to
+ --ll is a number specifying either a signal number or the exit
+ status of a process terminated by a signal. The --LL option is
+ equivalent to --ll. kkiillll returns true if at least one signal was
+ successfully sent, or false if an error occurs or an invalid op-
+ tion is encountered.
+
+ lleett _a_r_g [_a_r_g ...]
+ Each _a_r_g is an arithmetic expression to be evaluated (see AARRIITTHH--
+ MMEETTIICC EEVVAALLUUAATTIIOONN above). If the last _a_r_g evaluates to 0, lleett
+ returns 1; 0 is returned otherwise.
+
+ llooccaall [_o_p_t_i_o_n] [_n_a_m_e[=_v_a_l_u_e] ... | - ]
+ For each argument, a local variable named _n_a_m_e is created, and
+ assigned _v_a_l_u_e. The _o_p_t_i_o_n can be any of the options accepted
+ by ddeeccllaarree. When llooccaall is used within a function, it causes the
+ variable _n_a_m_e to have a visible scope restricted to that func-
+ tion and its children. If _n_a_m_e is -, the set of shell options
+ is made local to the function in which llooccaall is invoked: shell
+ options changed using the sseett builtin inside the function are
+ restored to their original values when the function returns.
+ The restore is effected as if a series of sseett commands were exe-
+ cuted to restore the values that were in place before the func-
+ tion. With no operands, llooccaall writes a list of local variables
+ to the standard output. It is an error to use llooccaall when not
+ within a function. The return status is 0 unless llooccaall is used
+ outside a function, an invalid _n_a_m_e is supplied, or _n_a_m_e is a
+ readonly variable.
+
+ llooggoouutt Exit a login shell.
+
+ mmaappffiillee [--dd _d_e_l_i_m] [--nn _c_o_u_n_t] [--OO _o_r_i_g_i_n] [--ss _c_o_u_n_t] [--tt] [--uu _f_d] [--CC
+ _c_a_l_l_b_a_c_k] [--cc _q_u_a_n_t_u_m] [_a_r_r_a_y]
+ rreeaaddaarrrraayy [--dd _d_e_l_i_m] [--nn _c_o_u_n_t] [--OO _o_r_i_g_i_n] [--ss _c_o_u_n_t] [--tt] [--uu _f_d] [--CC
+ _c_a_l_l_b_a_c_k] [--cc _q_u_a_n_t_u_m] [_a_r_r_a_y]
+ Read lines from the standard input into the indexed array vari-
+ able _a_r_r_a_y, or from file descriptor _f_d if the --uu option is sup-
+ plied. The variable MMAAPPFFIILLEE is the default _a_r_r_a_y. Options, if
+ supplied, have the following meanings:
+ --dd The first character of _d_e_l_i_m is used to terminate each
+ input line, rather than newline. If _d_e_l_i_m is the empty
+ string, mmaappffiillee will terminate a line when it reads a NUL
+ character.
+ --nn Copy at most _c_o_u_n_t lines. If _c_o_u_n_t is 0, all lines are
+ copied.
+ --OO Begin assigning to _a_r_r_a_y at index _o_r_i_g_i_n. The default
+ index is 0.
+ --ss Discard the first _c_o_u_n_t lines read.
+ --tt Remove a trailing _d_e_l_i_m (default newline) from each line
+ read.
+ --uu Read lines from file descriptor _f_d instead of the stan-
+ dard input.
+ --CC Evaluate _c_a_l_l_b_a_c_k each time _q_u_a_n_t_u_m lines are read. The
+ --cc option specifies _q_u_a_n_t_u_m.
+ --cc Specify the number of lines read between each call to
+ _c_a_l_l_b_a_c_k.
+
+ If --CC is specified without --cc, the default quantum is 5000.
+ When _c_a_l_l_b_a_c_k is evaluated, it is supplied the index of the next
+ array element to be assigned and the line to be assigned to that
+ element as additional arguments. _c_a_l_l_b_a_c_k is evaluated after
+ the line is read but before the array element is assigned.
+
+ If not supplied with an explicit origin, mmaappffiillee will clear _a_r_-
+ _r_a_y before assigning to it.
+
+ mmaappffiillee returns successfully unless an invalid option or option
+ argument is supplied, _a_r_r_a_y is invalid or unassignable, or if
+ _a_r_r_a_y is not an indexed array.
+
+ ppooppdd [-nn] [+_n] [-_n]
+ Removes entries from the directory stack. With no arguments,
+ removes the top directory from the stack, and performs a ccdd to
+ the new top directory. Arguments, if supplied, have the follow-
+ ing meanings:
+ --nn Suppresses the normal change of directory when removing
+ directories from the stack, so that only the stack is ma-
+ nipulated.
+ ++_n Removes the _nth entry counting from the left of the list
+ shown by ddiirrss, starting with zero. For example: ``popd
+ +0'' removes the first directory, ``popd +1'' the second.
+ --_n Removes the _nth entry counting from the right of the list
+ shown by ddiirrss, starting with zero. For example: ``popd
+ -0'' removes the last directory, ``popd -1'' the next to
+ last.
+
+ If the ppooppdd command is successful, a ddiirrss is performed as well,
+ and the return status is 0. ppooppdd returns false if an invalid
+ option is encountered, the directory stack is empty, a non-exis-
+ tent directory stack entry is specified, or the directory change
+ fails.
+
+ pprriinnttff [--vv _v_a_r] _f_o_r_m_a_t [_a_r_g_u_m_e_n_t_s]
+ Write the formatted _a_r_g_u_m_e_n_t_s to the standard output under the
+ control of the _f_o_r_m_a_t. The --vv option causes the output to be
+ assigned to the variable _v_a_r rather than being printed to the
+ standard output.
+
+ The _f_o_r_m_a_t is a character string which contains three types of
+ objects: plain characters, which are simply copied to standard
+ output, character escape sequences, which are converted and
+ copied to the standard output, and format specifications, each
+ of which causes printing of the next successive _a_r_g_u_m_e_n_t. In
+ addition to the standard _p_r_i_n_t_f(1) format specifications, pprriinnttff
+ interprets the following extensions:
+ %%bb causes pprriinnttff to expand backslash escape sequences in the
+ corresponding _a_r_g_u_m_e_n_t in the same way as eecchhoo --ee.
+ %%qq causes pprriinnttff to output the corresponding _a_r_g_u_m_e_n_t in a
+ format that can be reused as shell input.
+ %%((_d_a_t_e_f_m_t))TT
+ causes pprriinnttff to output the date-time string resulting
+ from using _d_a_t_e_f_m_t as a format string for _s_t_r_f_t_i_m_e(3).
+ The corresponding _a_r_g_u_m_e_n_t is an integer representing the
+ number of seconds since the epoch. Two special argument
+ values may be used: -1 represents the current time, and
+ -2 represents the time the shell was invoked. If no ar-
+ gument is specified, conversion behaves as if -1 had been
+ given. This is an exception to the usual pprriinnttff behav-
+ ior.
+
+ The %b, %q, and %T directives all use the field width and preci-
+ sion arguments from the format specification and write that many
+ bytes from (or use that wide a field for) the expanded argument,
+ which usually contains more characters than the original.
+
+ Arguments to non-string format specifiers are treated as C con-
+ stants, except that a leading plus or minus sign is allowed, and
+ if the leading character is a single or double quote, the value
+ is the ASCII value of the following character.
+
+ The _f_o_r_m_a_t is reused as necessary to consume all of the _a_r_g_u_-
+ _m_e_n_t_s. If the _f_o_r_m_a_t requires more _a_r_g_u_m_e_n_t_s than are supplied,
+ the extra format specifications behave as if a zero value or
+ null string, as appropriate, had been supplied. The return
+ value is zero on success, non-zero on failure.
+
+ ppuusshhdd [--nn] [+_n] [-_n]
+ ppuusshhdd [--nn] [_d_i_r]
+ Adds a directory to the top of the directory stack, or rotates
+ the stack, making the new top of the stack the current working
+ directory. With no arguments, ppuusshhdd exchanges the top two di-
+ rectories and returns 0, unless the directory stack is empty.
+ Arguments, if supplied, have the following meanings:
+ --nn Suppresses the normal change of directory when rotating
+ or adding directories to the stack, so that only the
+ stack is manipulated.
+ ++_n Rotates the stack so that the _nth directory (counting
+ from the left of the list shown by ddiirrss, starting with
+ zero) is at the top.
+ --_n Rotates the stack so that the _nth directory (counting
+ from the right of the list shown by ddiirrss, starting with
+ zero) is at the top.
+ _d_i_r Adds _d_i_r to the directory stack at the top, making it the
+ new current working directory as if it had been supplied
+ as the argument to the ccdd builtin.
+
+ If the ppuusshhdd command is successful, a ddiirrss is performed as well.
+ If the first form is used, ppuusshhdd returns 0 unless the cd to _d_i_r
+ fails. With the second form, ppuusshhdd returns 0 unless the direc-
+ tory stack is empty, a non-existent directory stack element is
+ specified, or the directory change to the specified new current
+ directory fails.
+
+ ppwwdd [--LLPP]
+ Print the absolute pathname of the current working directory.
+ The pathname printed contains no symbolic links if the --PP option
+ is supplied or the --oo pphhyyssiiccaall option to the sseett builtin command
+ is enabled. If the --LL option is used, the pathname printed may
+ contain symbolic links. The return status is 0 unless an error
+ occurs while reading the name of the current directory or an in-
+ valid option is supplied.
+
+ rreeaadd [--eerrss] [--aa _a_n_a_m_e] [--dd _d_e_l_i_m] [--ii _t_e_x_t] [--nn _n_c_h_a_r_s] [--NN _n_c_h_a_r_s] [--pp
+ _p_r_o_m_p_t] [--tt _t_i_m_e_o_u_t] [--uu _f_d] [_n_a_m_e ...]
+ One line is read from the standard input, or from the file de-
+ scriptor _f_d supplied as an argument to the --uu option, split into
+ words as described above under WWoorrdd SSpplliittttiinngg, and the first
+ word is assigned to the first _n_a_m_e, the second word to the sec-
+ ond _n_a_m_e, and so on. If there are more words than names, the
+ remaining words and their intervening delimiters are assigned to
+ the last _n_a_m_e. If there are fewer words read from the input
+ stream than names, the remaining names are assigned empty val-
+ ues. The characters in IIFFSS are used to split the line into
+ words using the same rules the shell uses for expansion (de-
+ scribed above under WWoorrdd SSpplliittttiinngg). The backslash character
+ (\\) may be used to remove any special meaning for the next char-
+ acter read and for line continuation. Options, if supplied,
+ have the following meanings:
+ --aa _a_n_a_m_e
+ The words are assigned to sequential indices of the array
+ variable _a_n_a_m_e, starting at 0. _a_n_a_m_e is unset before any
+ new values are assigned. Other _n_a_m_e arguments are ig-
+ nored.
+ --dd _d_e_l_i_m
+ The first character of _d_e_l_i_m is used to terminate the in-
+ put line, rather than newline. If _d_e_l_i_m is the empty
+ string, rreeaadd will terminate a line when it reads a NUL
+ character.
+ --ee If the standard input is coming from a terminal, rreeaaddlliinnee
+ (see RREEAADDLLIINNEE above) is used to obtain the line. Read-
+ line uses the current (or default, if line editing was
+ not previously active) editing settings, but uses Read-
+ line's default filename completion.
+ --ii _t_e_x_t
+ If rreeaaddlliinnee is being used to read the line, _t_e_x_t is
+ placed into the editing buffer before editing begins.
+ --nn _n_c_h_a_r_s
+ rreeaadd returns after reading _n_c_h_a_r_s characters rather than
+ waiting for a complete line of input, but honors a delim-
+ iter if fewer than _n_c_h_a_r_s characters are read before the
+ delimiter.
+ --NN _n_c_h_a_r_s
+ rreeaadd returns after reading exactly _n_c_h_a_r_s characters
+ rather than waiting for a complete line of input, unless
+ EOF is encountered or rreeaadd times out. Delimiter charac-
+ ters encountered in the input are not treated specially
+ and do not cause rreeaadd to return until _n_c_h_a_r_s characters
+ are read. The result is not split on the characters in
+ IIFFSS; the intent is that the variable is assigned exactly
+ the characters read (with the exception of backslash; see
+ the --rr option below).
+ --pp _p_r_o_m_p_t
+ Display _p_r_o_m_p_t on standard error, without a trailing new-
+ line, before attempting to read any input. The prompt is
+ displayed only if input is coming from a terminal.
+ --rr Backslash does not act as an escape character. The back-
+ slash is considered to be part of the line. In particu-
+ lar, a backslash-newline pair may not then be used as a
+ line continuation.
+ --ss Silent mode. If input is coming from a terminal, charac-
+ ters are not echoed.
+ --tt _t_i_m_e_o_u_t
+ Cause rreeaadd to time out and return failure if a complete
+ line of input (or a specified number of characters) is
+ not read within _t_i_m_e_o_u_t seconds. _t_i_m_e_o_u_t may be a deci-
+ mal number with a fractional portion following the deci-
+ mal point. This option is only effective if rreeaadd is
+ reading input from a terminal, pipe, or other special
+ file; it has no effect when reading from regular files.
+ If rreeaadd times out, rreeaadd saves any partial input read into
+ the specified variable _n_a_m_e. If _t_i_m_e_o_u_t is 0, rreeaadd re-
+ turns immediately, without trying to read any data. The
+ exit status is 0 if input is available on the specified
+ file descriptor, non-zero otherwise. The exit status is
+ greater than 128 if the timeout is exceeded.
+ --uu _f_d Read input from file descriptor _f_d.
+
+ If no _n_a_m_e_s are supplied, the line read, without the ending de-
+ limiter but otherwise unmodified, is assigned to the variable
+ RREEPPLLYY. The exit status is zero, unless end-of-file is encoun-
+ tered, rreeaadd times out (in which case the status is greater than
+ 128), a variable assignment error (such as assigning to a read-
+ only variable) occurs, or an invalid file descriptor is supplied
+ as the argument to --uu.
+
+ rreeaaddoonnllyy [--aaAAff] [--pp] [_n_a_m_e[=_w_o_r_d] ...]
+ The given _n_a_m_e_s are marked readonly; the values of these _n_a_m_e_s
+ may not be changed by subsequent assignment. If the --ff option
+ is supplied, the functions corresponding to the _n_a_m_e_s are so
+ marked. The --aa option restricts the variables to indexed ar-
+ rays; the --AA option restricts the variables to associative ar-
+ rays. If both options are supplied, --AA takes precedence. If no
+ _n_a_m_e arguments are given, or if the --pp option is supplied, a
+ list of all readonly names is printed. The other options may be
+ used to restrict the output to a subset of the set of readonly
+ names. The --pp option causes output to be displayed in a format
+ that may be reused as input. If a variable name is followed by
+ =_w_o_r_d, the value of the variable is set to _w_o_r_d. The return
+ status is 0 unless an invalid option is encountered, one of the
+ _n_a_m_e_s is not a valid shell variable name, or --ff is supplied with
+ a _n_a_m_e that is not a function.
+
+ rreettuurrnn [_n]
+ Causes a function to stop executing and return the value speci-
+ fied by _n to its caller. If _n is omitted, the return status is
+ that of the last command executed in the function body. If rree--
+ ttuurrnn is executed by a trap handler, the last command used to de-
+ termine the status is the last command executed before the trap
+ handler. If rreettuurrnn is executed during a DDEEBBUUGG trap, the last
+ command used to determine the status is the last command exe-
+ cuted by the trap handler before rreettuurrnn was invoked. If rreettuurrnn
+ is used outside a function, but during execution of a script by
+ the .. (ssoouurrccee) command, it causes the shell to stop executing
+ that script and return either _n or the exit status of the last
+ command executed within the script as the exit status of the
+ script. If _n is supplied, the return value is its least signif-
+ icant 8 bits. The return status is non-zero if rreettuurrnn is sup-
+ plied a non-numeric argument, or is used outside a function and
+ not during execution of a script by .. or ssoouurrccee. Any command
+ associated with the RREETTUURRNN trap is executed before execution re-
+ sumes after the function or script.
+
+ sseett [----aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [--oo _o_p_t_i_o_n_-_n_a_m_e] [_a_r_g ...]
+ sseett [++aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [++oo _o_p_t_i_o_n_-_n_a_m_e] [_a_r_g ...]
+ Without options, the name and value of each shell variable are
+ displayed in a format that can be reused as input for setting or
+ resetting the currently-set variables. Read-only variables can-
+ not be reset. In _p_o_s_i_x _m_o_d_e, only shell variables are listed.
+ The output is sorted according to the current locale. When op-
+ tions are specified, they set or unset shell attributes. Any
+ arguments remaining after option processing are treated as val-
+ ues for the positional parameters and are assigned, in order, to
+ $$11, $$22, ...... $$_n. Options, if specified, have the following
+ meanings:
+ --aa Each variable or function that is created or modified is
+ given the export attribute and marked for export to the
+ environment of subsequent commands.
+ --bb Report the status of terminated background jobs immedi-
+ ately, rather than before the next primary prompt. This
+ is effective only when job control is enabled.
+ --ee Exit immediately if a _p_i_p_e_l_i_n_e (which may consist of a
+ single _s_i_m_p_l_e _c_o_m_m_a_n_d), a _l_i_s_t, or a _c_o_m_p_o_u_n_d _c_o_m_m_a_n_d
+ (see SSHHEELLLL GGRRAAMMMMAARR above), exits with a non-zero status.
+ The shell does not exit if the command that fails is
+ part of the command list immediately following a wwhhiillee
+ or uunnttiill keyword, part of the test following the iiff or
+ eelliiff reserved words, part of any command executed in a
+ &&&& or |||| list except the command following the final &&&&
+ or ||||, any command in a pipeline but the last, or if the
+ command's return value is being inverted with !!. If a
+ compound command other than a subshell returns a non-
+ zero status because a command failed while --ee was being
+ ignored, the shell does not exit. A trap on EERRRR, if
+ set, is executed before the shell exits. This option
+ applies to the shell environment and each subshell envi-
+ ronment separately (see CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONNMMEENNTT
+ above), and may cause subshells to exit before executing
+ all the commands in the subshell.
+
+ If a compound command or shell function executes in a
+ context where --ee is being ignored, none of the commands
+ executed within the compound command or function body
+ will be affected by the --ee setting, even if --ee is set
+ and a command returns a failure status. If a compound
+ command or shell function sets --ee while executing in a
+ context where --ee is ignored, that setting will not have
+ any effect until the compound command or the command
+ containing the function call completes.
+ --ff Disable pathname expansion.
+ --hh Remember the location of commands as they are looked up
+ for execution. This is enabled by default.
+ --kk All arguments in the form of assignment statements are
+ placed in the environment for a command, not just those
+ that precede the command name.
+ --mm Monitor mode. Job control is enabled. This option is
+ on by default for interactive shells on systems that
+ support it (see JJOOBB CCOONNTTRROOLL above). All processes run
+ in a separate process group. When a background job com-
+ pletes, the shell prints a line containing its exit sta-
+ tus.
+ --nn Read commands but do not execute them. This may be used
+ to check a shell script for syntax errors. This is ig-
+ nored by interactive shells.
+ --oo _o_p_t_i_o_n_-_n_a_m_e
+ The _o_p_t_i_o_n_-_n_a_m_e can be one of the following:
+ aalllleexxppoorrtt
+ Same as --aa.
+ bbrraacceeeexxppaanndd
+ Same as --BB.
+ eemmaaccss Use an emacs-style command line editing inter-
+ face. This is enabled by default when the shell
+ is interactive, unless the shell is started with
+ the ----nnooeeddiittiinngg option. This also affects the
+ editing interface used for rreeaadd --ee.
+ eerrrreexxiitt Same as --ee.
+ eerrrrttrraaccee
+ Same as --EE.
+ ffuunnccttrraaccee
+ Same as --TT.
+ hhaasshhaallll Same as --hh.
+ hhiisstteexxppaanndd
+ Same as --HH.
+ hhiissttoorryy Enable command history, as described above under
+ HHIISSTTOORRYY. This option is on by default in inter-
+ active shells.
+ iiggnnoorreeeeooff
+ The effect is as if the shell command ``IG-
+ NOREEOF=10'' had been executed (see SShheellll VVaarrii--
+ aabblleess above).
+ kkeeyywwoorrdd Same as --kk.
+ mmoonniittoorr Same as --mm.
+ nnoocclloobbbbeerr
+ Same as --CC.
+ nnooeexxeecc Same as --nn.
+ nnoogglloobb Same as --ff.
+ nnoolloogg Currently ignored.
+ nnoottiiffyy Same as --bb.
+ nnoouunnsseett Same as --uu.
+ oonneeccmmdd Same as --tt.
+ pphhyyssiiccaall
+ Same as --PP.
+ ppiippeeffaaiill
+ If set, the return value of a pipeline is the
+ value of the last (rightmost) command to exit
+ with a non-zero status, or zero if all commands
+ in the pipeline exit successfully. This option
+ is disabled by default.
+ ppoossiixx Change the behavior of bbaasshh where the default
+ operation differs from the POSIX standard to
+ match the standard (_p_o_s_i_x _m_o_d_e). See SSEEEE AALLSSOO
+ below for a reference to a document that details
+ how posix mode affects bash's behavior.
+ pprriivviilleeggeedd
+ Same as --pp.
+ vveerrbboossee Same as --vv.
+ vvii Use a vi-style command line editing interface.
+ This also affects the editing interface used for
+ rreeaadd --ee.
+ xxttrraaccee Same as --xx.
+ If --oo is supplied with no _o_p_t_i_o_n_-_n_a_m_e, the values of the
+ current options are printed. If ++oo is supplied with no
+ _o_p_t_i_o_n_-_n_a_m_e, a series of sseett commands to recreate the
+ current option settings is displayed on the standard
+ output.
+ --pp Turn on _p_r_i_v_i_l_e_g_e_d mode. In this mode, the $$EENNVV and
+ $$BBAASSHH__EENNVV files are not processed, shell functions are
+ not inherited from the environment, and the SSHHEELLLLOOPPTTSS,
+ BBAASSHHOOPPTTSS, CCDDPPAATTHH, and GGLLOOBBIIGGNNOORREE variables, if they ap-
+ pear in the environment, are ignored. If the shell is
+ started with the effective user (group) id not equal to
+ the real user (group) id, and the --pp option is not sup-
+ plied, these actions are taken and the effective user id
+ is set to the real user id. If the --pp option is sup-
+ plied at startup, the effective user id is not reset.
+ Turning this option off causes the effective user and
+ group ids to be set to the real user and group ids.
+ --tt Exit after reading and executing one command.
+ --uu Treat unset variables and parameters other than the spe-
+ cial parameters "@" and "*" as an error when performing
+ parameter expansion. If expansion is attempted on an
+ unset variable or parameter, the shell prints an error
+ message, and, if not interactive, exits with a non-zero
+ status.
+ --vv Print shell input lines as they are read.
+ --xx After expanding each _s_i_m_p_l_e _c_o_m_m_a_n_d, ffoorr command, ccaassee
+ command, sseelleecctt command, or arithmetic ffoorr command, dis-
+ play the expanded value of PPSS44, followed by the command
+ and its expanded arguments or associated word list.
+ --BB The shell performs brace expansion (see BBrraaccee EExxppaannssiioonn
+ above). This is on by default.
+ --CC If set, bbaasshh does not overwrite an existing file with
+ the >>, >>&&, and <<>> redirection operators. This may be
+ overridden when creating output files by using the redi-
+ rection operator >>|| instead of >>.
+ --EE If set, any trap on EERRRR is inherited by shell functions,
+ command substitutions, and commands executed in a sub-
+ shell environment. The EERRRR trap is normally not inher-
+ ited in such cases.
+ --HH Enable !! style history substitution. This option is on
+ by default when the shell is interactive.
+ --PP If set, the shell does not resolve symbolic links when
+ executing commands such as ccdd that change the current
+ working directory. It uses the physical directory
+ structure instead. By default, bbaasshh follows the logical
+ chain of directories when performing commands which
+ change the current directory.
+ --TT If set, any traps on DDEEBBUUGG and RREETTUURRNN are inherited by
+ shell functions, command substitutions, and commands ex-
+ ecuted in a subshell environment. The DDEEBBUUGG and RREETTUURRNN
+ traps are normally not inherited in such cases.
+ ---- If no arguments follow this option, then the positional
+ parameters are unset. Otherwise, the positional parame-
+ ters are set to the _a_r_gs, even if some of them begin
+ with a --.
+ -- Signal the end of options, cause all remaining _a_r_gs to
+ be assigned to the positional parameters. The --xx and --vv
+ options are turned off. If there are no _a_r_gs, the posi-
+ tional parameters remain unchanged.
+
+ The options are off by default unless otherwise noted. Using +
+ rather than - causes these options to be turned off. The op-
+ tions can also be specified as arguments to an invocation of the
+ shell. The current set of options may be found in $$--. The re-
+ turn status is always true unless an invalid option is encoun-
+ tered.
+
+ sshhiifftt [_n]
+ The positional parameters from _n+1 ... are renamed to $$11 ........
+ Parameters represented by the numbers $$## down to $$##-_n+1 are un-
+ set. _n must be a non-negative number less than or equal to $$##.
+ If _n is 0, no parameters are changed. If _n is not given, it is
+ assumed to be 1. If _n is greater than $$##, the positional param-
+ eters are not changed. The return status is greater than zero
+ if _n is greater than $$## or less than zero; otherwise 0.
+
+ sshhoopptt [--ppqqssuu] [--oo] [_o_p_t_n_a_m_e ...]
+ Toggle the values of settings controlling optional shell behav-
+ ior. The settings can be either those listed below, or, if the
+ --oo option is used, those available with the --oo option to the sseett
+ builtin command. With no options, or with the --pp option, a list
+ of all settable options is displayed, with an indication of
+ whether or not each is set; if _o_p_t_n_a_m_e_s are supplied, the output
+ is restricted to those options. The --pp option causes output to
+ be displayed in a form that may be reused as input. Other op-
+ tions have the following meanings:
+ --ss Enable (set) each _o_p_t_n_a_m_e.
+ --uu Disable (unset) each _o_p_t_n_a_m_e.
+ --qq Suppresses normal output (quiet mode); the return status
+ indicates whether the _o_p_t_n_a_m_e is set or unset. If multi-
+ ple _o_p_t_n_a_m_e arguments are given with --qq, the return sta-
+ tus is zero if all _o_p_t_n_a_m_e_s are enabled; non-zero other-
+ wise.
+ --oo Restricts the values of _o_p_t_n_a_m_e to be those defined for
+ the --oo option to the sseett builtin.
+
+ If either --ss or --uu is used with no _o_p_t_n_a_m_e arguments, sshhoopptt
+ shows only those options which are set or unset, respectively.
+ Unless otherwise noted, the sshhoopptt options are disabled (unset)
+ by default.
+
+ The return status when listing options is zero if all _o_p_t_n_a_m_e_s
+ are enabled, non-zero otherwise. When setting or unsetting op-
+ tions, the return status is zero unless an _o_p_t_n_a_m_e is not a
+ valid shell option.
+
+ The list of sshhoopptt options is:
+
+ aassssoocc__eexxppaanndd__oonnccee
+ If set, the shell suppresses multiple evaluation of as-
+ sociative array subscripts during arithmetic expression
+ evaluation, while executing builtins that can perform
+ variable assignments, and while executing builtins that
+ perform array dereferencing.
+ aauuttooccdd If set, a command name that is the name of a directory
+ is executed as if it were the argument to the ccdd com-
+ mand. This option is only used by interactive shells.
+ ccddaabbllee__vvaarrss
+ If set, an argument to the ccdd builtin command that is
+ not a directory is assumed to be the name of a variable
+ whose value is the directory to change to.
+ ccddssppeellll If set, minor errors in the spelling of a directory com-
+ ponent in a ccdd command will be corrected. The errors
+ checked for are transposed characters, a missing charac-
+ ter, and one character too many. If a correction is
+ found, the corrected filename is printed, and the com-
+ mand proceeds. This option is only used by interactive
+ shells.
+ cchheecckkhhaasshh
+ If set, bbaasshh checks that a command found in the hash ta-
+ ble exists before trying to execute it. If a hashed
+ command no longer exists, a normal path search is per-
+ formed.
+ cchheecckkjjoobbss
+ If set, bbaasshh lists the status of any stopped and running
+ jobs before exiting an interactive shell. If any jobs
+ are running, this causes the exit to be deferred until a
+ second exit is attempted without an intervening command
+ (see JJOOBB CCOONNTTRROOLL above). The shell always postpones ex-
+ iting if any jobs are stopped.
+ cchheecckkwwiinnssiizzee
+ If set, bbaasshh checks the window size after each external
+ (non-builtin) command and, if necessary, updates the
+ values of LLIINNEESS and CCOOLLUUMMNNSS. This option is enabled by
+ default.
+ ccmmddhhiisstt If set, bbaasshh attempts to save all lines of a multiple-
+ line command in the same history entry. This allows
+ easy re-editing of multi-line commands. This option is
+ enabled by default, but only has an effect if command
+ history is enabled, as described above under HHIISSTTOORRYY.
+ ccoommppaatt3311
+ ccoommppaatt3322
+ ccoommppaatt4400
+ ccoommppaatt4411
+ ccoommppaatt4422
+ ccoommppaatt4433
+ ccoommppaatt4444
+ These control aspects of the shell's compatibility mode
+ (see SSHHEELLLL CCOOMMPPAATTIIBBIILLIITTYY MMOODDEE below).
+
+ ccoommpplleettee__ffuullllqquuoottee
+ If set, bbaasshh quotes all shell metacharacters in file-
+ names and directory names when performing completion.
+ If not set, bbaasshh removes metacharacters such as the dol-
+ lar sign from the set of characters that will be quoted
+ in completed filenames when these metacharacters appear
+ in shell variable references in words to be completed.
+ This means that dollar signs in variable names that ex-
+ pand to directories will not be quoted; however, any
+ dollar signs appearing in filenames will not be quoted,
+ either. This is active only when bash is using back-
+ slashes to quote completed filenames. This variable is
+ set by default, which is the default bash behavior in
+ versions through 4.2.
+
+ ddiirreexxppaanndd
+ If set, bbaasshh replaces directory names with the results
+ of word expansion when performing filename completion.
+ This changes the contents of the readline editing buf-
+ fer. If not set, bbaasshh attempts to preserve what the
+ user typed.
+
+ ddiirrssppeellll
+ If set, bbaasshh attempts spelling correction on directory
+ names during word completion if the directory name ini-
+ tially supplied does not exist.
+
+ ddoottgglloobb If set, bbaasshh includes filenames beginning with a `.' in
+ the results of pathname expansion. The filenames ````..''''
+ and ````....'''' must always be matched explicitly, even if
+ ddoottgglloobb is set.
+
+ eexxeeccffaaiill
+ If set, a non-interactive shell will not exit if it can-
+ not execute the file specified as an argument to the
+ eexxeecc builtin command. An interactive shell does not
+ exit if eexxeecc fails.
+
+ eexxppaanndd__aalliiaasseess
+ If set, aliases are expanded as described above under
+ AALLIIAASSEESS. This option is enabled by default for interac-
+ tive shells.
+
+ eexxttddeebbuugg
+ If set at shell invocation, or in a shell startup file,
+ arrange to execute the debugger profile before the shell
+ starts, identical to the ----ddeebbuuggggeerr option. If set af-
+ ter invocation, behavior intended for use by debuggers
+ is enabled:
+
+ 11.. The --FF option to the ddeeccllaarree builtin displays the
+ source file name and line number corresponding to
+ each function name supplied as an argument.
+
+ 22.. If the command run by the DDEEBBUUGG trap returns a
+ non-zero value, the next command is skipped and
+ not executed.
+
+ 33.. If the command run by the DDEEBBUUGG trap returns a
+ value of 2, and the shell is executing in a sub-
+ routine (a shell function or a shell script exe-
+ cuted by the .. or ssoouurrccee builtins), the shell
+ simulates a call to rreettuurrnn.
+
+ 44.. BBAASSHH__AARRGGCC and BBAASSHH__AARRGGVV are updated as described
+ in their descriptions above.
+
+ 55.. Function tracing is enabled: command substitu-
+ tion, shell functions, and subshells invoked with
+ (( _c_o_m_m_a_n_d )) inherit the DDEEBBUUGG and RREETTUURRNN traps.
+
+ 66.. Error tracing is enabled: command substitution,
+ shell functions, and subshells invoked with ((
+ _c_o_m_m_a_n_d )) inherit the EERRRR trap.
+
+ eexxttgglloobb If set, the extended pattern matching features described
+ above under PPaatthhnnaammee EExxppaannssiioonn are enabled.
+
+ eexxttqquuoottee
+ If set, $$'_s_t_r_i_n_g' and $$"_s_t_r_i_n_g" quoting is performed
+ within $${{_p_a_r_a_m_e_t_e_r}} expansions enclosed in double
+ quotes. This option is enabled by default.
+
+ ffaaiillgglloobb
+ If set, patterns which fail to match filenames during
+ pathname expansion result in an expansion error.
+
+ ffoorrccee__ffiiggnnoorree
+ If set, the suffixes specified by the FFIIGGNNOORREE shell
+ variable cause words to be ignored when performing word
+ completion even if the ignored words are the only possi-
+ ble completions. See SSHHEELLLL VVAARRIIAABBLLEESS above for a de-
+ scription of FFIIGGNNOORREE. This option is enabled by de-
+ fault.
+
+ gglloobbaasscciiiirraannggeess
+ If set, range expressions used in pattern matching
+ bracket expressions (see PPaatttteerrnn MMaattcchhiinngg above) behave
+ as if in the traditional C locale when performing com-
+ parisons. That is, the current locale's collating se-
+ quence is not taken into account, so bb will not collate
+ between AA and BB, and upper-case and lower-case ASCII
+ characters will collate together.
+
+ gglloobbssttaarr
+ If set, the pattern **** used in a pathname expansion con-
+ text will match all files and zero or more directories
+ and subdirectories. If the pattern is followed by a //,
+ only directories and subdirectories match.
+
+ ggnnuu__eerrrrffmmtt
+ If set, shell error messages are written in the standard
+ GNU error message format.
+
+ hhiissttaappppeenndd
+ If set, the history list is appended to the file named
+ by the value of the HHIISSTTFFIILLEE variable when the shell ex-
+ its, rather than overwriting the file.
+
+ hhiissttrreeeeddiitt
+ If set, and rreeaaddlliinnee is being used, a user is given the
+ opportunity to re-edit a failed history substitution.
+
+ hhiissttvveerriiffyy
+ If set, and rreeaaddlliinnee is being used, the results of his-
+ tory substitution are not immediately passed to the
+ shell parser. Instead, the resulting line is loaded
+ into the rreeaaddlliinnee editing buffer, allowing further modi-
+ fication.
+
+ hhoossttccoommpplleettee
+ If set, and rreeaaddlliinnee is being used, bbaasshh will attempt to
+ perform hostname completion when a word containing a @@
+ is being completed (see CCoommpplleettiinngg under RREEAADDLLIINNEE
+ above). This is enabled by default.
+
+ hhuuppoonneexxiitt
+ If set, bbaasshh will send SSIIGGHHUUPP to all jobs when an inter-
+ active login shell exits.
+
+ iinnhheerriitt__eerrrreexxiitt
+ If set, command substitution inherits the value of the
+ eerrrreexxiitt option, instead of unsetting it in the subshell
+ environment. This option is enabled when _p_o_s_i_x _m_o_d_e is
+ enabled.
+
+ iinntteerraaccttiivvee__ccoommmmeennttss
+ If set, allow a word beginning with ## to cause that word
+ and all remaining characters on that line to be ignored
+ in an interactive shell (see CCOOMMMMEENNTTSS above). This op-
+ tion is enabled by default.
+
+ llaassttppiippee
+ If set, and job control is not active, the shell runs
+ the last command of a pipeline not executed in the back-
+ ground in the current shell environment.
+
+ lliitthhiisstt If set, and the ccmmddhhiisstt option is enabled, multi-line
+ commands are saved to the history with embedded newlines
+ rather than using semicolon separators where possible.
+
+ llooccaallvvaarr__iinnhheerriitt
+ If set, local variables inherit the value and attributes
+ of a variable of the same name that exists at a previous
+ scope before any new value is assigned. The nameref at-
+ tribute is not inherited.
+
+ llooccaallvvaarr__uunnsseett
+ If set, calling uunnsseett on local variables in previous
+ function scopes marks them so subsequent lookups find
+ them unset until that function returns. This is identi-
+ cal to the behavior of unsetting local variables at the
+ current function scope.
+
+ llooggiinn__sshheellll
+ The shell sets this option if it is started as a login
+ shell (see IINNVVOOCCAATTIIOONN above). The value may not be
+ changed.
+
+ mmaaiillwwaarrnn
+ If set, and a file that bbaasshh is checking for mail has
+ been accessed since the last time it was checked, the
+ message ``The mail in _m_a_i_l_f_i_l_e has been read'' is dis-
+ played.
+
+ nnoo__eemmppttyy__ccmmdd__ccoommpplleettiioonn
+ If set, and rreeaaddlliinnee is being used, bbaasshh will not at-
+ tempt to search the PPAATTHH for possible completions when
+ completion is attempted on an empty line.
+
+ nnooccaasseegglloobb
+ If set, bbaasshh matches filenames in a case-insensitive
+ fashion when performing pathname expansion (see PPaatthhnnaammee
+ EExxppaannssiioonn above).
+
+ nnooccaasseemmaattcchh
+ If set, bbaasshh matches patterns in a case-insensitive
+ fashion when performing matching while executing ccaassee or
+ [[[[ conditional commands, when performing pattern substi-
+ tution word expansions, or when filtering possible com-
+ pletions as part of programmable completion.
+
+ nnuullllgglloobb
+ If set, bbaasshh allows patterns which match no files (see
+ PPaatthhnnaammee EExxppaannssiioonn above) to expand to a null string,
+ rather than themselves.
+
+ pprrooggccoommpp
+ If set, the programmable completion facilities (see PPrroo--
+ ggrraammmmaabbllee CCoommpplleettiioonn above) are enabled. This option is
+ enabled by default.
+
+ pprrooggccoommpp__aalliiaass
+ If set, and programmable completion is enabled, bbaasshh
+ treats a command name that doesn't have any completions
+ as a possible alias and attempts alias expansion. If it
+ has an alias, bbaasshh attempts programmable completion us-
+ ing the command word resulting from the expanded alias.
+
+ pprroommppttvvaarrss
+ If set, prompt strings undergo parameter expansion, com-
+ mand substitution, arithmetic expansion, and quote re-
+ moval after being expanded as described in PPRROOMMPPTTIINNGG
+ above. This option is enabled by default.
+
+ rreessttrriicctteedd__sshheellll
+ The shell sets this option if it is started in re-
+ stricted mode (see RREESSTTRRIICCTTEEDD SSHHEELLLL below). The value
+ may not be changed. This is not reset when the startup
+ files are executed, allowing the startup files to dis-
+ cover whether or not a shell is restricted.
+
+ sshhiifftt__vveerrbboossee
+ If set, the sshhiifftt builtin prints an error message when
+ the shift count exceeds the number of positional parame-
+ ters.
+
+ ssoouurrcceeppaatthh
+ If set, the ssoouurrccee (..) builtin uses the value of PPAATTHH to
+ find the directory containing the file supplied as an
+ argument. This option is enabled by default.
+
+ xxppgg__eecchhoo
+ If set, the eecchhoo builtin expands backslash-escape se-
+ quences by default.
+
+ ssuussppeenndd [--ff]
+ Suspend the execution of this shell until it receives a SSIIGGCCOONNTT
+ signal. A login shell cannot be suspended; the --ff option can be
+ used to override this and force the suspension. The return sta-
+ tus is 0 unless the shell is a login shell and --ff is not sup-
+ plied, or if job control is not enabled.
+
+ tteesstt _e_x_p_r
+ [[ _e_x_p_r ]]
+ Return a status of 0 (true) or 1 (false) depending on the evalu-
+ ation of the conditional expression _e_x_p_r. Each operator and op-
+ erand must be a separate argument. Expressions are composed of
+ the primaries described in the bbaasshh manual page under CCOONNDDII--
+ TTIIOONNAALL EEXXPPRREESSSSIIOONNSS. tteesstt does not accept any options, nor does
+ it accept and ignore an argument of ---- as signifying the end of
+ options.
+
+ Expressions may be combined using the following operators,
+ listed in decreasing order of precedence. The evaluation de-
+ pends on the number of arguments; see below. Operator prece-
+ dence is used when there are five or more arguments.
+ !! _e_x_p_r True if _e_x_p_r is false.
+ (( _e_x_p_r ))
+ Returns the value of _e_x_p_r. This may be used to override
+ the normal precedence of operators.
+ _e_x_p_r_1 -aa _e_x_p_r_2
+ True if both _e_x_p_r_1 and _e_x_p_r_2 are true.
+ _e_x_p_r_1 -oo _e_x_p_r_2
+ True if either _e_x_p_r_1 or _e_x_p_r_2 is true.
+
+ tteesstt and [[ evaluate conditional expressions using a set of rules
+ based on the number of arguments.
+
+ 0 arguments
+ The expression is false.
+ 1 argument
+ The expression is true if and only if the argument is not
+ null.
+ 2 arguments
+ If the first argument is !!, the expression is true if and
+ only if the second argument is null. If the first argu-
+ ment is one of the unary conditional operators listed
+ above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the expression is
+ true if the unary test is true. If the first argument is
+ not a valid unary conditional operator, the expression is
+ false.
+ 3 arguments
+ The following conditions are applied in the order listed.
+ If the second argument is one of the binary conditional
+ operators listed above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the
+ result of the expression is the result of the binary test
+ using the first and third arguments as operands. The --aa
+ and --oo operators are considered binary operators when
+ there are three arguments. If the first argument is !!,
+ the value is the negation of the two-argument test using
+ the second and third arguments. If the first argument is
+ exactly (( and the third argument is exactly )), the result
+ is the one-argument test of the second argument. Other-
+ wise, the expression is false.
+ 4 arguments
+ If the first argument is !!, the result is the negation of
+ the three-argument expression composed of the remaining
+ arguments. Otherwise, the expression is parsed and eval-
+ uated according to precedence using the rules listed
+ above.
+ 5 or more arguments
+ The expression is parsed and evaluated according to
+ precedence using the rules listed above.
+
+ When used with tteesstt or [[, the << and >> operators sort lexico-
+ graphically using ASCII ordering.
+
+ ttiimmeess Print the accumulated user and system times for the shell and
+ for processes run from the shell. The return status is 0.
+
+ ttrraapp [--llpp] [[_a_r_g] _s_i_g_s_p_e_c ...]
+ The command _a_r_g is to be read and executed when the shell re-
+ ceives signal(s) _s_i_g_s_p_e_c. If _a_r_g is absent (and there is a sin-
+ gle _s_i_g_s_p_e_c) or --, each specified signal is reset to its origi-
+ nal disposition (the value it had upon entrance to the shell).
+ If _a_r_g is the null string the signal specified by each _s_i_g_s_p_e_c
+ is ignored by the shell and by the commands it invokes. If _a_r_g
+ is not present and --pp has been supplied, then the trap commands
+ associated with each _s_i_g_s_p_e_c are displayed. If no arguments are
+ supplied or if only --pp is given, ttrraapp prints the list of com-
+ mands associated with each signal. The --ll option causes the
+ shell to print a list of signal names and their corresponding
+ numbers. Each _s_i_g_s_p_e_c is either a signal name defined in <_s_i_g_-
+ _n_a_l_._h>, or a signal number. Signal names are case insensitive
+ and the SSIIGG prefix is optional.
+
+ If a _s_i_g_s_p_e_c is EEXXIITT (0) the command _a_r_g is executed on exit
+ from the shell. If a _s_i_g_s_p_e_c is DDEEBBUUGG, the command _a_r_g is exe-
+ cuted before every _s_i_m_p_l_e _c_o_m_m_a_n_d, _f_o_r command, _c_a_s_e command,
+ _s_e_l_e_c_t command, every arithmetic _f_o_r command, and before the
+ first command executes in a shell function (see SSHHEELLLL GGRRAAMMMMAARR
+ above). Refer to the description of the eexxttddeebbuugg option to the
+ sshhoopptt builtin for details of its effect on the DDEEBBUUGG trap. If a
+ _s_i_g_s_p_e_c is RREETTUURRNN, the command _a_r_g is executed each time a shell
+ function or a script executed with the .. or ssoouurrccee builtins fin-
+ ishes executing.
+
+ If a _s_i_g_s_p_e_c is EERRRR, the command _a_r_g is executed whenever a
+ pipeline (which may consist of a single simple command), a list,
+ or a compound command returns a non-zero exit status, subject to
+ the following conditions. The EERRRR trap is not executed if the
+ failed command is part of the command list immediately following
+ a wwhhiillee or uunnttiill keyword, part of the test in an _i_f statement,
+ part of a command executed in a &&&& or |||| list except the command
+ following the final &&&& or ||||, any command in a pipeline but the
+ last, or if the command's return value is being inverted using
+ !!. These are the same conditions obeyed by the eerrrreexxiitt (--ee) op-
+ tion.
+
+ Signals ignored upon entry to the shell cannot be trapped or re-
+ set. Trapped signals that are not being ignored are reset to
+ their original values in a subshell or subshell environment when
+ one is created. The return status is false if any _s_i_g_s_p_e_c is
+ invalid; otherwise ttrraapp returns true.
+
+ ttyyppee [--aaffttppPP] _n_a_m_e [_n_a_m_e ...]
+ With no options, indicate how each _n_a_m_e would be interpreted if
+ used as a command name. If the --tt option is used, ttyyppee prints a
+ string which is one of _a_l_i_a_s, _k_e_y_w_o_r_d, _f_u_n_c_t_i_o_n, _b_u_i_l_t_i_n, or
+ _f_i_l_e if _n_a_m_e is an alias, shell reserved word, function,
+ builtin, or disk file, respectively. If the _n_a_m_e is not found,
+ then nothing is printed, and an exit status of false is re-
+ turned. If the --pp option is used, ttyyppee either returns the name
+ of the disk file that would be executed if _n_a_m_e were specified
+ as a command name, or nothing if ``type -t name'' would not re-
+ turn _f_i_l_e. The --PP option forces a PPAATTHH search for each _n_a_m_e,
+ even if ``type -t name'' would not return _f_i_l_e. If a command is
+ hashed, --pp and --PP print the hashed value, which is not necessar-
+ ily the file that appears first in PPAATTHH. If the --aa option is
+ used, ttyyppee prints all of the places that contain an executable
+ named _n_a_m_e. This includes aliases and functions, if and only if
+ the --pp option is not also used. The table of hashed commands is
+ not consulted when using --aa. The --ff option suppresses shell
+ function lookup, as with the ccoommmmaanndd builtin. ttyyppee returns true
+ if all of the arguments are found, false if any are not found.
+
+ uulliimmiitt [--HHSS] --aa
+ uulliimmiitt [--HHSS] [--bbccddeeffiikkllmmnnppqqrrssttuuvvxxPPRRTT [_l_i_m_i_t]]
+ Provides control over the resources available to the shell and
+ to processes started by it, on systems that allow such control.
+ The --HH and --SS options specify that the hard or soft limit is set
+ for the given resource. A hard limit cannot be increased by a
+ non-root user once it is set; a soft limit may be increased up
+ to the value of the hard limit. If neither --HH nor --SS is speci-
+ fied, both the soft and hard limits are set. The value of _l_i_m_i_t
+ can be a number in the unit specified for the resource or one of
+ the special values hhaarrdd, ssoofftt, or uunnlliimmiitteedd, which stand for the
+ current hard limit, the current soft limit, and no limit, re-
+ spectively. If _l_i_m_i_t is omitted, the current value of the soft
+ limit of the resource is printed, unless the --HH option is given.
+ When more than one resource is specified, the limit name and
+ unit, if appropriate, are printed before the value. Other op-
+ tions are interpreted as follows:
+ --aa All current limits are reported; no limits are set
+ --bb The maximum socket buffer size
+ --cc The maximum size of core files created
+ --dd The maximum size of a process's data segment
+ --ee The maximum scheduling priority ("nice")
+ --ff The maximum size of files written by the shell and its
+ children
+ --ii The maximum number of pending signals
+ --kk The maximum number of kqueues that may be allocated
+ --ll The maximum size that may be locked into memory
+ --mm The maximum resident set size (many systems do not honor
+ this limit)
+ --nn The maximum number of open file descriptors (most systems
+ do not allow this value to be set)
+ --pp The pipe size in 512-byte blocks (this may not be set)
+ --qq The maximum number of bytes in POSIX message queues
+ --rr The maximum real-time scheduling priority
+ --ss The maximum stack size
+ --tt The maximum amount of cpu time in seconds
+ --uu The maximum number of processes available to a single
+ user
+ --vv The maximum amount of virtual memory available to the
+ shell and, on some systems, to its children
+ --xx The maximum number of file locks
+ --PP The maximum number of pseudoterminals
+ --RR The maximum time a real-time process can run before
+ blocking, in microseconds
+ --TT The maximum number of threads
+
+ If _l_i_m_i_t is given, and the --aa option is not used, _l_i_m_i_t is the
+ new value of the specified resource. If no option is given,
+ then --ff is assumed. Values are in 1024-byte increments, except
+ for --tt, which is in seconds; --RR, which is in microseconds; --pp,
+ which is in units of 512-byte blocks; --PP, --TT, --bb, --kk, --nn, and
+ --uu, which are unscaled values; and, when in posix mode, --cc and
+ --ff, which are in 512-byte increments. The return status is 0
+ unless an invalid option or argument is supplied, or an error
+ occurs while setting a new limit.
+
+ uummaasskk [--pp] [--SS] [_m_o_d_e]
+ The user file-creation mask is set to _m_o_d_e. If _m_o_d_e begins with
+ a digit, it is interpreted as an octal number; otherwise it is
+ interpreted as a symbolic mode mask similar to that accepted by
+ _c_h_m_o_d(1). If _m_o_d_e is omitted, the current value of the mask is
+ printed. The --SS option causes the mask to be printed in sym-
+ bolic form; the default output is an octal number. If the --pp
+ option is supplied, and _m_o_d_e is omitted, the output is in a form
+ that may be reused as input. The return status is 0 if the mode
+ was successfully changed or if no _m_o_d_e argument was supplied,
+ and false otherwise.
+
+ uunnaalliiaass [-aa] [_n_a_m_e ...]
+ Remove each _n_a_m_e from the list of defined aliases. If --aa is
+ supplied, all alias definitions are removed. The return value
+ is true unless a supplied _n_a_m_e is not a defined alias.
+
+ uunnsseett [-ffvv] [-nn] [_n_a_m_e ...]
+ For each _n_a_m_e, remove the corresponding variable or function.
+ If the --vv option is given, each _n_a_m_e refers to a shell variable,
+ and that variable is removed. Read-only variables may not be
+ unset. If --ff is specified, each _n_a_m_e refers to a shell func-
+ tion, and the function definition is removed. If the --nn option
+ is supplied, and _n_a_m_e is a variable with the _n_a_m_e_r_e_f attribute,
+ _n_a_m_e will be unset rather than the variable it references. --nn
+ has no effect if the --ff option is supplied. If no options are
+ supplied, each _n_a_m_e refers to a variable; if there is no vari-
+ able by that name, a function with that name, if any, is unset.
+ Each unset variable or function is removed from the environment
+ passed to subsequent commands. If any of BBAASSHH__AALLIIAASSEESS,
+ BBAASSHH__AARRGGVV00, BBAASSHH__CCMMDDSS, BBAASSHH__CCOOMMMMAANNDD, BBAASSHH__SSUUBBSSHHEELLLL, BBAASSHHPPIIDD,
+ CCOOMMPP__WWOORRDDBBRREEAAKKSS, DDIIRRSSTTAACCKK, EEPPOOCCHHRREEAALLTTIIMMEE, EEPPOOCCHHSSEECCOONNDDSS, FFUUNNCC--
+ NNAAMMEE, GGRROOUUPPSS, HHIISSTTCCMMDD, LLIINNEENNOO, RRAANNDDOOMM, SSEECCOONNDDSS, or SSRRAANNDDOOMM are
+ unset, they lose their special properties, even if they are sub-
+ sequently reset. The exit status is true unless a _n_a_m_e is read-
+ only.
+
+ wwaaiitt [--ffnn] [--pp _v_a_r_n_a_m_e] [_i_d _._._.]
+ Wait for each specified child process and return its termination
+ status. Each _i_d may be a process ID or a job specification; if
+ a job spec is given, all processes in that job's pipeline are
+ waited for. If _i_d is not given, wwaaiitt waits for all running
+ background jobs and the last-executed process substitution, if
+ its process id is the same as $$!!, and the return status is zero.
+ If the --nn option is supplied, wwaaiitt waits for a single job from
+ the list of _i_ds or, if no _i_ds are supplied, any job, to complete
+ and returns its exit status. If none of the supplied arguments
+ is a child of the shell, or if no arguments are supplied and the
+ shell has no unwaited-for children, the exit status is 127. If
+ the --pp option is supplied, the process or job identifier of the
+ job for which the exit status is returned is assigned to the
+ variable _v_a_r_n_a_m_e named by the option argument. The variable
+ will be unset initially, before any assignment. This is useful
+ only when the --nn option is supplied. Supplying the --ff option,
+ when job control is enabled, forces wwaaiitt to wait for _i_d to ter-
+ minate before returning its status, instead of returning when it
+ changes status. If _i_d specifies a non-existent process or job,
+ the return status is 127. Otherwise, the return status is the
+ exit status of the last process or job waited for.
+
+SSHHEELLLL CCOOMMPPAATTIIBBIILLIITTYY MMOODDEE
+ Bash-4.0 introduced the concept of a `shell compatibility level', spec-
+ ified as a set of options to the shopt builtin ccoommppaatt3311, ccoommppaatt3322, ccoomm--
+ ppaatt4400, ccoommppaatt4411, and so on). There is only one current compatibility
+ level -- each option is mutually exclusive. The compatibility level is
+ intended to allow users to select behavior from previous versions that
+ is incompatible with newer versions while they migrate scripts to use
+ current features and behavior. It's intended to be a temporary solu-
+ tion.
+
+ This section does not mention behavior that is standard for a particu-
+ lar version (e.g., setting ccoommppaatt3322 means that quoting the rhs of the
+ regexp matching operator quotes special regexp characters in the word,
+ which is default behavior in bash-3.2 and above).
+
+ If a user enables, say, ccoommppaatt3322, it may affect the behavior of other
+ compatibility levels up to and including the current compatibility
+ level. The idea is that each compatibility level controls behavior
+ that changed in that version of bbaasshh, but that behavior may have been
+ present in earlier versions. For instance, the change to use locale-
+ based comparisons with the [[[[ command came in bash-4.1, and earlier
+ versions used ASCII-based comparisons, so enabling ccoommppaatt3322 will enable
+ ASCII-based comparisons as well. That granularity may not be suffi-
+ cient for all uses, and as a result users should employ compatibility
+ levels carefully. Read the documentation for a particular feature to
+ find out the current behavior.
+
+ Bash-4.3 introduced a new shell variable: BBAASSHH__CCOOMMPPAATT. The value as-
+ signed to this variable (a decimal version number like 4.2, or an inte-
+ ger corresponding to the ccoommppaatt_N_N option, like 42) determines the com-
+ patibility level.
+
+ Starting with bash-4.4, Bash has begun deprecating older compatibility
+ levels. Eventually, the options will be removed in favor of BBAASSHH__CCOOMM--
+ PPAATT.
+
+ Bash-5.0 is the final version for which there will be an individual
+ shopt option for the previous version. Users should use BBAASSHH__CCOOMMPPAATT on
+ bash-5.0 and later versions.
+
+ The following table describes the behavior changes controlled by each
+ compatibility level setting. The ccoommppaatt_N_N tag is used as shorthand for
+ setting the compatibility level to _N_N using one of the following mecha-
+ nisms. For versions prior to bash-5.0, the compatibility level may be
+ set using the corresponding ccoommppaatt_N_N shopt option. For bash-4.3 and
+ later versions, the BBAASSHH__CCOOMMPPAATT variable is preferred, and it is re-
+ quired for bash-5.1 and later versions.
+
+ ccoommppaatt3311
+ +o quoting the rhs of the [[[[ command's regexp matching oper-
+ ator (=~) has no special effect
+
+ ccoommppaatt3322
+ +o interrupting a command list such as "a ; b ; c" causes
+ the execution of the next command in the list (in
+ bash-4.0 and later versions, the shell acts as if it re-
+ ceived the interrupt, so interrupting one command in a
+ list aborts the execution of the entire list)
+
+ ccoommppaatt4400
+ +o the << and >> operators to the [[[[ command do not consider
+ the current locale when comparing strings; they use ASCII
+ ordering. Bash versions prior to bash-4.1 use ASCII col-
+ lation and _s_t_r_c_m_p(3); bash-4.1 and later use the current
+ locale's collation sequence and _s_t_r_c_o_l_l(3).
+
+ ccoommppaatt4411
+ +o in _p_o_s_i_x mode, ttiimmee may be followed by options and still
+ be recognized as a reserved word (this is POSIX interpre-
+ tation 267)
+ +o in _p_o_s_i_x mode, the parser requires that an even number of
+ single quotes occur in the _w_o_r_d portion of a double-
+ quoted parameter expansion and treats them specially, so
+ that characters within the single quotes are considered
+ quoted (this is POSIX interpretation 221)
+
+ ccoommppaatt4422
+ +o the replacement string in double-quoted pattern substitu-
+ tion does not undergo quote removal, as it does in ver-
+ sions after bash-4.2
+ +o in posix mode, single quotes are considered special when
+ expanding the _w_o_r_d portion of a double-quoted parameter
+ expansion and can be used to quote a closing brace or
+ other special character (this is part of POSIX interpre-
+ tation 221); in later versions, single quotes are not
+ special within double-quoted word expansions
+
+ ccoommppaatt4433
+ +o the shell does not print a warning message if an attempt
+ is made to use a quoted compound assignment as an argu-
+ ment to declare (declare -a foo='(1 2)'). Later versions
+ warn that this usage is deprecated
+ +o word expansion errors are considered non-fatal errors
+ that cause the current command to fail, even in posix
+ mode (the default behavior is to make them fatal errors
+ that cause the shell to exit)
+ +o when executing a shell function, the loop state
+ (while/until/etc.) is not reset, so bbrreeaakk or ccoonnttiinnuuee in
+ that function will break or continue loops in the calling
+ context. Bash-4.4 and later reset the loop state to pre-
+ vent this
+
+ ccoommppaatt4444
+ +o the shell sets up the values used by BBAASSHH__AARRGGVV and
+ BBAASSHH__AARRGGCC so they can expand to the shell's positional
+ parameters even if extended debugging mode is not enabled
+ +o a subshell inherits loops from its parent context, so
+ bbrreeaakk or ccoonnttiinnuuee will cause the subshell to exit.
+ Bash-5.0 and later reset the loop state to prevent the
+ exit
+ +o variable assignments preceding builtins like eexxppoorrtt and
+ rreeaaddoonnllyy that set attributes continue to affect variables
+ with the same name in the calling environment even if the
+ shell is not in posix mode
+
+ ccoommppaatt5500
+ +o Bash-5.1 changed the way $$RRAANNDDOOMM is generated to intro-
+ duce slightly more randomness. If the shell compatibility
+ level is set to 50 or lower, it reverts to the method
+ from bash-5.0 and previous versions, so seeding the ran-
+ dom number generator by assigning a value to RRAANNDDOOMM will
+ produce the same sequence as in bash-5.0
+ +o If the command hash table is empty, bash versions prior
+ to bash-5.1 printed an informational message to that ef-
+ fect, even when producing output that can be reused as
+ input. Bash-5.1 suppresses that message when the --ll op-
+ tion is supplied.
+
+SSEEEE AALLSSOO
+ bash(1), sh(1)
+
+
+
+GNU Bash 5.0 2004 Apr 20 BASH_BUILTINS(1)