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🏷️ NAME

env - run a program in a modified environment

🚀 Quick Reference

Use Case	Command	Description
🧹 Run with empty environment	env -i command	Start with no environment variables
🔧 Set custom environment variables	env NAME=VALUE command	Run command with modified environment
❌ Remove a variable	env -u NAME command	Unset a specific environment variable
📂 Change working directory	env -C DIR command	Run command in different directory
🔗 Split string for shebang	#!/usr/bin/env -S perl -w -T	Pass multiple arguments in script shebang
🚦 Handle signals	env --default-signal=PIPE seq inf | head -n1	Reset signal handler to default
📋 Print environment	env	Display current environment (no command)

🔧 SYNOPSIS

env [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]

📖 DESCRIPTION

Set each NAME to VALUE in the environment and run COMMAND.

Mandatory arguments to long options are mandatory for short options too.

🧹 -i, --ignore-environment
Start with an empty environment

🔌 -0, --null
End each output line with NUL, not newline

❌ -u, --unset=NAME
Remove variable from the environment

📂 -C, --chdir=DIR
Change working directory to DIR

✂️ -S, --split-string=S
Process and split S into separate arguments; used to pass multiple arguments on she‑bang lines

🚫 --block-signal[=SIG]
Block delivery of SIG signal(s) to COMMAND

🔄 --default-signal[=SIG]
Reset handling of SIG signal(s) to the default

🤫 --ignore-signal[=SIG]
Set handling of SIG signals(s) to do nothing

📋 --list-signal-handling
List non‑default signal handling to stderr

🐞 -v, --debug
Print verbose information for each processing step

❓ --help
Display this help and exit

📟 --version
Output version information and exit

🔁 A mere - implies -i. If no COMMAND, print the resulting environment.

⚠️ SIG may be a signal name like PIPE, or a signal number like 13. Without SIG, all known signals are included. Multiple signals can be comma‑separated.

⚙️ OPTIONS

✂️ -S/--split-string usage in scripts

The -S option allows specifying multiple parameters in a script. Running a script named 1.pl containing the following first line:

#!/usr/bin/env -S perl -w -T
...

Will execute perl -w -T 1.pl.

Without the -S parameter the script will likely fail with:

/usr/bin/env: 'perl -w -T': No such file or directory

See the full documentation for more details.

🔄 --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.

sh -c 'env --default-signal=PIPE seq inf | head -n1'

📝 NOTES

POSIX's exec(2) pages says:

“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.”

✍️ AUTHOR

Written by Richard Mlynarik, David MacKenzie, and Assaf Gordon.

🐛 REPORTING BUGS

GNU coreutils online help: https://www.gnu.org/software/coreutils/
Report any translation bugs to https://translationproject.org/team/

©️ COPYRIGHT

Copyright © 2020 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later https://gnu.org/licenses/gpl.html.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

📚 SEE ALSO

sigaction(2), sigprocmask(2), signal(7)

Full documentation: https://www.gnu.org/software/coreutils/env
or available locally via: info '(coreutils) env invocation'

🏷️ NAME 🚀 Quick Reference 🔧 SYNOPSIS 📖 DESCRIPTION ⚙️ OPTIONS 📝 NOTES ✍️ AUTHOR 🐛 REPORTING BUGS ©️ COPYRIGHT 📚 SEE ALSO