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+# Contributed by Noah Friedman.
+
+# To avoid using a function in bash, you can use the `builtin' or
+# `command' builtins, but neither guarantees that you use an external
+# program instead of a bash builtin if there's a builtin by that name. So
+# this function can be used like `command' except that it guarantees the
+# program is external by first disabling any builtin by that name. After
+# the command is done executing, the state of the builtin is restored.
+function external ()
+{
+ local state=""
+ local exit_status
+
+ if builtin_p "$1"; then
+ state="builtin"
+ enable -n "$1"
+ fi
+
+ command "$@"
+ exit_status=$?
+
+ if [ "$state" = "builtin" ]; then
+ enable "$1"
+ fi
+
+ return ${exit_status}
+}
+
+# What is does is tell you if a particular keyword is currently enabled as
+# a shell builtin. It does NOT tell you if invoking that keyword will
+# necessarily run the builtin. For that, do something like
+#
+# test "$(builtin type -type [keyword])" = "builtin"
+#
+# Note also, that disabling a builtin with "enable -n" will make builtin_p
+# return false, since the builtin is no longer available.
+function builtin_p ()
+{
+ local word
+
+ set $(builtin type -all -type "$1")
+
+ for word in "$@" ; do
+ if [ "${word}" = "builtin" ]; then
+ return 0
+ fi
+ done
+
+ return 1
+}