Adding upstream version 9.1.upstream/9.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 67 insertions, 0 deletions

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+'\" Copyright (C) 1998-2022 Free Software Foundation, Inc.
+'\"
+'\" This is free software.  You may redistribute copies of it under the terms
+'\" of the GNU General Public License <https://www.gnu.org/licenses/gpl.html>.
+'\" There is NO WARRANTY, to the extent permitted by law.
+[NAME]
+env \- run a program in a modified environment
+[DESCRIPTION]
+.\" Add any additional description here
+[OPTIONS]
+.SS "\-S/\-\-split\-string usage in scripts"
+The
+.B \-S
+option allows specifying multiple parameters in a script.
+Running a script named
+.B 1.pl
+containing the following first line:
+.PP
+.RS
+.nf
+#!/usr/bin/env \-S perl \-w \-T
+\&...
+.fi
+.RE
+.PP
+Will execute
+.B "perl \-w \-T 1.pl".
+.PP
+Without the
+.B '\-S'
+parameter the script will likely fail with:
+.PP
+.RS
+.nf
+/usr/bin/env: 'perl \-w \-T': No such file or directory
+.fi
+.RE
+.PP
+See the full documentation for more details.
+.PP
+.SS "\-\-default-signal[=SIG]" usage
+This option allows setting a signal handler to its default
+action, which is not possible using the traditional shell
+trap command.  The following example ensures that seq
+will be terminated by SIGPIPE no matter how this signal
+is being handled in the process invoking the command.
+
+.PP
+.RS
+.nf
+sh \-c 'env \-\-default-signal=PIPE seq inf | head \-n1'
+.fi
+.RE
+.PP
+
+[NOTES]
+POSIX's exec(3p) pages says:
+.RS
+"many existing applications wrongly assume that they start with certain
+signals set to the default action and/or unblocked.... Therefore, it is best
+not to block or ignore signals across execs without explicit reason to do so,
+and especially not to block signals across execs of arbitrary (not closely
+cooperating) programs."
+.RE
+
+[SEE ALSO]
+sigaction(2), sigprocmask(2), signal(7)