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coreutils/man/env.x

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maint: update all copyright year number ranges Run "make update-copyright" and then... * gnulib: Update to latest with copyright year adjusted. * tests/init.sh: Sync with gnulib to pick up copyright year. * bootstrap: Likewise. * tests/sample-test: Adjust to use the single most recent year.
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'\" Copyright (C) 1998-2021 Free Software Foundation, Inc.
env: add -S/--split-string option Adopted from FreeBSD's env(1), useful for specifing multiple parameters on a shebang (#!) script line, e.g: #!/usr/bin/env -S perl -w -T Discussed in https://lists.gnu.org/r/coreutils/2018-04/msg00011.html * src/env.c (valid_escape_sequence,escape_char,scan_varname, extract_varname,validate_split_str,build_argv, parse_split_string): New functions. (main): Process new option and call parse_split_string. (usage): Mention new option. * tests/misc/env-S.pl: Test new option from the command line. * tests/misc/env-S-script.sh: Test new option from shebang scripts. * tests/local.mk (all_tests): Add new tests. * man/env.x (OPTIONS): Show a brief example of -S usage and point to the full documentation for more information. * doc/coreutils.texi (env invocation): Detail usage of -S/--split-string option. * NEWS: Mention new option.
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'\"
'\" 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.
include summary in [NAME] section
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[NAME]
env \- run a program in a modified environment
.
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[DESCRIPTION]
.\" Add any additional description here
env: add -S/--split-string option Adopted from FreeBSD's env(1), useful for specifing multiple parameters on a shebang (#!) script line, e.g: #!/usr/bin/env -S perl -w -T Discussed in https://lists.gnu.org/r/coreutils/2018-04/msg00011.html * src/env.c (valid_escape_sequence,escape_char,scan_varname, extract_varname,validate_split_str,build_argv, parse_split_string): New functions. (main): Process new option and call parse_split_string. (usage): Mention new option. * tests/misc/env-S.pl: Test new option from the command line. * tests/misc/env-S-script.sh: Test new option from shebang scripts. * tests/local.mk (all_tests): Add new tests. * man/env.x (OPTIONS): Show a brief example of -S usage and point to the full documentation for more information. * doc/coreutils.texi (env invocation): Detail usage of -S/--split-string option. * NEWS: Mention new option.
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[OPTIONS]
.SS "\-S/\-\-split\-string usage in scripts"
The
.B \-S
doc: fix minor mistakes in "env.x" * man/env.x (OPTIONS): Fix a spelling mistake. Protect a period at the beginning of a line.
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option allows specifying multiple parameters in a script.
env: add -S/--split-string option Adopted from FreeBSD's env(1), useful for specifing multiple parameters on a shebang (#!) script line, e.g: #!/usr/bin/env -S perl -w -T Discussed in https://lists.gnu.org/r/coreutils/2018-04/msg00011.html * src/env.c (valid_escape_sequence,escape_char,scan_varname, extract_varname,validate_split_str,build_argv, parse_split_string): New functions. (main): Process new option and call parse_split_string. (usage): Mention new option. * tests/misc/env-S.pl: Test new option from the command line. * tests/misc/env-S-script.sh: Test new option from shebang scripts. * tests/local.mk (all_tests): Add new tests. * man/env.x (OPTIONS): Show a brief example of -S usage and point to the full documentation for more information. * doc/coreutils.texi (env invocation): Detail usage of -S/--split-string option. * NEWS: Mention new option.
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Running a script named
.B 1.pl
containing the following first line:
.PP
.RS
.nf
#!/usr/bin/env \-S perl \-w \-T
doc: fix minor mistakes in "env.x" * man/env.x (OPTIONS): Fix a spelling mistake. Protect a period at the beginning of a line.
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\&...
env: add -S/--split-string option Adopted from FreeBSD's env(1), useful for specifing multiple parameters on a shebang (#!) script line, e.g: #!/usr/bin/env -S perl -w -T Discussed in https://lists.gnu.org/r/coreutils/2018-04/msg00011.html * src/env.c (valid_escape_sequence,escape_char,scan_varname, extract_varname,validate_split_str,build_argv, parse_split_string): New functions. (main): Process new option and call parse_split_string. (usage): Mention new option. * tests/misc/env-S.pl: Test new option from the command line. * tests/misc/env-S-script.sh: Test new option from shebang scripts. * tests/local.mk (all_tests): Add new tests. * man/env.x (OPTIONS): Show a brief example of -S usage and point to the full documentation for more information. * doc/coreutils.texi (env invocation): Detail usage of -S/--split-string option. * NEWS: Mention new option.
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.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.
env: new options --{default,ignore,block}-signal[=SIG] New options to set signal handlers for the command being executed. --block-signal suggested by Paul Eggert in http://bugs.gnu.org/34488#71 --default-signal is useful to overcome the POSIX limitation that shell must not override inherited signal state, e.g. the second 'trap' here is a no-op: trap '' PIPE && sh -c 'trap - PIPE ; seq inf | head -n1' Instead use: trap '' PIPE && sh -c 'env --default-signal=PIPE seq inf | head -n1' Similarly, the following will prevent CTRL-C from terminating the program: env --ignore-signal=INT seq inf > /dev/null See https://bugs.gnu.org/34488#8 * NEWS: Mention new options. * doc/coreutils.texi (env invocation): Document new options. * man/env.x: Add example of --default-signal=SIG usage. (SEE ALSO): Mention sigprocmask. * src/env.c (signals): New global variable. (longopts): Add new options. (usage): Print new options. (parse_signal_params): Parse comma-separated list of signals, store in signals variable. (reset_signal_handlers): Set each signal to SIG_DFL/SIG_IGN. (parse_block_signal_params): Parse command-line options. (set_signal_proc_mask): Call sigprocmask to block/unblock signals. (main): Process new options. * src/local.mk (src_env_SOURCES): Add operand2sig.c. * tests/misc/env-signal-handler.sh: New test. * tests/local.mk (all_tests): Add new test.
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.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(2) 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)
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