ENV(1) General Commands Manual ENV(1)

env — set and print environment

env [-0i] [-C dir] [-u name] [--] [name=value ...] [--] [utility [argument ...]]

env executes utility, with the given arguments, after modifying the environment as specified on the command line. Each name=value option specifies an environment variable, name, with a value of value which may be empty, that is to replace an existing environment variable with the same name, or otherwise is to be added to the environment.

The ‘-i’ option causes env to completely ignore the environment it inherits.

The ‘-C dir’ option causes the working directory to be changed to dir, and the environment variable PWD to be removed from the environment.

The ‘-u name’ option causes removal of the name environment variable if it is in the environment. This is similar to the unset command in sh(1). The value for name must not include the ‘=’ character.

To allow for either a name to be added to the environment, or the utility's name (if no environment additions are present), to begin with a minus sign (‘-’) the first “--” argument is required. To allow for utility's name to contain an equals character (‘=’) (anywhere in its word) the second “--” is required. If there are no name=value arguments given, then to allow for utility to contain an equals character, both “--” arguments are required. The first ends the options, the second ends the (in this case empty) environment variable additions.

If no utility is specified, env prints out the names and values of the variables in the environment. Each name=value pair is separated by a new line unless -0 is specified, in which case name/value pairs are separated by a nul character (‘\0’). The -0 option is ignored if a utility is given.

If a utility is specified, can be located, and successfully invoked, the exit status of env is the exit status of the utility. See its documentation for the possible values and interpretations.

Otherwise env exits with one of the following values:

0
No utility was specified, and env has successfully written the contents of the (possibly modified) environment to standard output.
125
env was given an invalid option, a requested operation failed, or some other error occurred.
126
utility was found, but could not be invoked.
127
utility could not be found.

Whenever env exits with a non-zero status, without having invoked a utility, it writes a message to the standard error stream identifying itself, and the reason for the non-zero exit. This can help distinguish cases where env exits because of a problem, from when utility does so. The case of a zero exit status is simpler; if a utility was given on the command line, the zero status is from that utility, otherwise it is from env.

The historic - option has been deprecated but is still supported in this implementation.

The -C, -u and -0 options are non-standard extensions.

chdir(2), execvp(3), environ(7)

The env utility conforms to IEEE Std 1003.2-1992 (“POSIX.2”).

The env command appeared in 4.4BSD.

The -u and -0 options first appeared in NetBSD 10, after earlier appearing in other systems.

The -C option first appeared in NetBSD 10.1.

MOUSE February 9, 2025 ENV(1)