-.\" $NetBSD: env.1,v 1.6 1997/10/18 13:55:22 lukem Exp $
-.\"
-.\" Copyright (c) 1980, 1990 The Regents of the University of California.
-.\" All rights reserved.
+.\" Copyright (c) 1980, 1990, 1993
+.\" The Regents of the University of California. All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the Institute of Electrical and Electronics Engineers, Inc.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
-.\" 3. All advertising materials mentioning features or use of this software
-.\" must display the following acknowledgement:
-.\" This product includes software developed by the University of
-.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.\" from: @(#)printenv.1 6.7 (Berkeley) 7/28/91
-.\" $NetBSD: env.1,v 1.6 1997/10/18 13:55:22 lukem Exp $
+.\" From @(#)printenv.1 8.1 (Berkeley) 6/6/93
+.\" From FreeBSD: src/usr.bin/printenv/printenv.1,v 1.17 2002/11/26 17:33:35 ru Exp
+.\" $FreeBSD$
.\"
-.Dd August 27, 1993
+.Dd April 17, 2008
.Dt ENV 1
.Os
.Sh NAME
.Nm env
-.Nd set and print environment
+.Nd set environment and execute command, or print environment
.Sh SYNOPSIS
.Nm
-.Op Fl i
-.Op Ar name=value ...
-.Oo
-.Ar utility
-.Op argument ...
-.Oc
+.Op Fl iv
+.Op Fl P Ar altpath
+.Op Fl S Ar string
+.Op Fl u Ar name
+.Op Ar name Ns = Ns Ar value ...
+.Op Ar utility Op Ar argument ...
.Sh DESCRIPTION
+The
.Nm
-executes
+utility executes another
.Ar utility
after modifying the environment as
-specified on the command line. The option
-.Ar name=value
-specifies
-an environmental variable,
-.Ar name ,
+specified on the command line.
+Each
+.Ar name Ns = Ns Ar value
+option specifies the setting of an environment variable,
+.Ar name ,
with a value of
-.Ar value .
-The option
-.Sq Fl i
-causes
+.Ar value .
+All such environment variables are set before the
+.Ar utility
+is executed.
+.Pp
+The options are as follows:
+.Bl -tag -width indent
+.It Fl i
+Execute the
+.Ar utility
+with only those environment variables specified by
+.Ar name Ns = Ns Ar value
+options.
+The environment inherited
+by
+.Nm
+is ignored completely.
+.\" -P
+.It Fl P Ar altpath
+Search the set of directories as specified by
+.Ar altpath
+to locate the specified
+.Ar utility
+program, instead of using the value of the
+.Ev PATH
+environment variable.
+.\" -S
+.It Fl S Ar string
+Split apart the given
+.Ar string
+into multiple strings, and process each of the resulting strings
+as separate arguments to the
+.Nm
+utility.
+The
+.Fl S
+option recognizes some special character escape sequences and
+also supports environment-variable substitution, as described
+below.
+.\" -u
+.It Fl u Ar name
+If the environment variable
+.Ar name
+is in the environment, then remove it before processing the
+remaining options.
+This is similar to the
+.Ic unset
+command in
+.Xr sh 1 .
+The value for
+.Ar name
+must not include the
+.Ql =
+character.
+.\" -v
+.It Fl v
+Print verbose information for each step of processing done by the
.Nm
-to completely ignore the environment
-it inherits.
+utility.
+Additional information will be printed if
+.Fl v
+is specified multiple times.
+.El
+.Pp
+The above options are only recognized when they are specified
+before any
+.Ar name Ns = Ns Ar value
+options.
.Pp
-If no
+If no
.Ar utility
is specified,
.Nm
prints out the names and values
-of the variables in the environment, with one
-.Ar name=value
-pair per line.
-.Sh DIAGNOSTICS
-If the
-.Ar utility
-is invoked, the exit status of
+of the variables in the environment, with one name/value pair per line.
+.\"
+.Ss Details of Fl S Ss (split-string) processing
+The processing of the
+.Fl S
+option will split the given
+.Ar string
+into separate arguments based on any space or <tab> characters found in the
+.Ar string .
+Each of those new arguments will then be treated as if it had been
+specified as a separate argument on the original
.Nm
-shall be the exit status of
-.Ar utility;
-otherwise, the
+command.
+.Pp
+Spaces and tabs may be embedded in one of those new arguments by using
+single
+.Pq Dq Li '
+or double
+.Pq Ql \&"
+quotes, or backslashes
+.Pq Ql \e .
+Single quotes will escape all non-single quote characters, up to
+the matching single quote.
+Double quotes will escape all non-double quote characters, up to
+the matching double quote.
+It is an error if the end of the
+.Ar string
+is reached before the matching quote character.
+.Pp
+If
+.Fl S
+would create a new argument that starts with the
+.Ql #
+character, then that argument and the remainder of the
+.Ar string
+will be ignored.
+The
+.Ql \e#
+sequence can be used when you want a new argument to start
+with a
+.Ql #
+character, without causing the remainder of the
+.Ar string
+to be skipped.
+.Pp
+While processing the
+.Ar string
+value,
+.Fl S
+processing will treat certain character combinations as escape
+sequences which represent some action to take.
+The character escape sequences are in backslash notation.
+The characters and their meanings are as follows:
+.Pp
+.Bl -tag -width indent -offset indent -compact
+.It Cm \ec
+Ignore the remaining characters in the
+.Ar string .
+This must not appear inside a double-quoted string.
+.It Cm \ef
+Replace with a <form-feed> character.
+.It Cm \en
+Replace with a <new-line> character.
+.It Cm \er
+Replace with a <carriage return> character.
+.It Cm \et
+Replace with a <tab> character.
+.It Cm \ev
+Replace with a <vertical tab> character.
+.It Cm \e#
+Replace with a
+.Ql #
+character.
+This would be useful when you need a
+.Ql #
+as the first character in one of the arguments created
+by splitting apart the given
+.Ar string .
+.It Cm \e$
+Replace with a
+.Ql $
+character.
+.It Cm \e_
+If this is found inside of a double-quoted string, then replace it
+with a single blank.
+If this is found outside of a quoted string, then treat this as the
+separator character between new arguments in the original
+.Ar string .
+.It Cm \e"
+Replace with a <double quote> character.
+.It Cm \e\'
+Replace with a <single quote> character.
+.It Cm \e\e
+Replace with a backslash character.
+.El
+.Pp
+The sequences for <single-quote> and backslash are the only sequences
+which are recognized inside of a single-quoted string.
+The other sequences have no special meaning inside a single-quoted
+string.
+All escape sequences are recognized inside of a double-quoted string.
+It is an error if a single
+.Ql \e
+character is followed by a character other than the ones listed above.
+.Pp
+The processing of
+.Fl S
+also supports substitution of values from environment variables.
+To do this, the name of the environment variable must be inside of
+.Ql ${} ,
+such as:
+.Li ${SOMEVAR} .
+The common shell syntax of
+.Li $SOMEVAR
+is not supported.
+All values substituted will be the values of the environment variables
+as they were when the
.Nm
-utility exits with one of the following values:
-.Bl -tag -width Ds
-.It 0
-The
+utility was originally invoked.
+Those values will not be checked for any of the escape sequences as
+described above.
+And any settings of
+.Ar name Ns = Ns Ar value
+will not effect the values used for substitution in
+.Fl S
+processing.
+.Pp
+Also,
+.Fl S
+processing can not reference the value of the special parameters
+which are defined by most shells.
+For instance,
+.Fl S
+can not recognize special parameters such as:
+.Ql $* ,
+.Ql $@ ,
+.Ql $# ,
+.Ql $?
+or
+.Ql $$
+if they appear inside the given
+.Ar string .
+.\"
+.Ss Use in shell-scripts
+The
.Nm
-utility completed successfully
-.It 1-125
-An error occurred in the
+utility is often used as the
+.Ar interpreter
+on the first line of interpreted scripts, as
+described in
+.Xr execve 2 .
+.Pp
+Note that the way the kernel parses the
+.Ql #!
+(first line) of an interpreted script has changed as of
+.Fx 6.0 .
+Prior to that, the
+.Fx
+kernel would split that first line into separate arguments based
+on any whitespace (space or <tab> characters) found in the line.
+So, if a script named
+.Pa /usr/local/bin/someport
+had a first line of:
+.Pp
+.Dl "#!/usr/local/bin/php -n -q -dsafe_mode=0"
+.Pp
+then the
+.Pa /usr/local/bin/php
+program would have been started with the arguments of:
+.Bd -literal -offset indent
+arg[0] = '/usr/local/bin/php'
+arg[1] = '-n'
+arg[2] = '-q'
+arg[3] = '-dsafe_mode=0'
+arg[4] = '/usr/local/bin/someport'
+.Ed
+.Pp
+plus any arguments the user specified when executing
+.Pa someport .
+However, this processing of multiple options on the
+.Ql #!
+line is not the way any other operating system parses the
+first line of an interpreted script.
+So after a change which was made for
+.Fx 6.0
+release, that script will result in
+.Pa /usr/local/bin/php
+being started with the arguments of:
+.Bd -literal -offset indent
+arg[0] = '/usr/local/bin/php'
+arg[1] = '-n -q -dsafe_mode=0'
+arg[2] = '/usr/local/bin/someport'
+.Ed
+.Pp
+plus any arguments the user specified.
+This caused a significant change in the behavior of a few scripts.
+In the case of above script, to have it behave the same way under
+.Fx 6.0
+as it did under earlier releases, the first line should be
+changed to:
+.Pp
+.Dl "#!/usr/bin/env -S /usr/local/bin/php -n -q -dsafe_mode=0"
+.Pp
+The
.Nm
-utility.
-.It 126
-The utility specified by
-.Ar utility
-was found, but could not be invoked.
-.It 127
-The utility specified by
-.Ar utility
+utility will be started with the entire line as a single
+argument:
+.Pp
+.Dl "arg[1] = '-S /usr/local/bin/php -n -q -dsafe_mode=0'"
+.Pp
+and then
+.Fl S
+processing will split that line into separate arguments before
+executing
+.Pa /usr/local/bin/php .
+.\"
+.Sh ENVIRONMENT
+The
+.Nm
+utility uses the
+.Ev PATH
+environment variable to locate the requested
+.Ar utility
+if the name contains no
+.Ql /
+characters, unless the
+.Fl P
+option has been specified.
+.Sh EXIT STATUS
+.Ex -std
+An exit status of 126 indicates that
+.Ar utility
+was found, but could not be executed.
+An exit status of 127 indicates that
+.Ar utility
could not be found.
-.El
+.Sh EXAMPLES
+Since the
+.Nm
+utility is often used as part of the first line of an interpreted script,
+the following examples show a number of ways that the
+.Nm
+utility can be useful in scripts.
+.Pp
+The kernel processing of an interpreted script does not allow a script
+to directly reference some other script as its own interpreter.
+As a way around this, the main difference between
+.Pp
+.Dl #!/usr/local/bin/foo
+and
+.Dl "#!/usr/bin/env /usr/local/bin/foo"
+.Pp
+is that the latter works even if
+.Pa /usr/local/bin/foo
+is itself an interpreted script.
+.Pp
+Probably the most common use of
+.Nm
+is to find the correct interpreter for a script, when the interpreter
+may be in different directories on different systems.
+The following example will find the
+.Ql perl
+interpreter by searching through the directories specified by
+.Ev PATH .
+.Pp
+.Dl "#!/usr/bin/env perl"
+.Pp
+One limitation of that example is that it assumes the user's value
+for
+.Ev PATH
+is set to a value which will find the interpreter you want
+to execute.
+The
+.Fl P
+option can be used to make sure a specific list of directories is
+used in the search for
+.Ar utility .
+Note that the
+.Fl S
+option is also required for this example to work correctly.
+.Pp
+.Dl "#!/usr/bin/env -S -P/usr/local/bin:/usr/bin perl"
+.Pp
+The above finds
+.Ql perl
+only if it is in
+.Pa /usr/local/bin
+or
+.Pa /usr/bin .
+That could be combined with the present value of
+.Ev PATH ,
+to provide more flexibility.
+Note that spaces are not required between the
+.Fl S
+and
+.Fl P
+options:
+.Pp
+.Dl "#!/usr/bin/env -S-P/usr/local/bin:/usr/bin:${PATH} perl"
.Sh COMPATIBILITY
-The historic
-.Fl
-option has been deprecated but is still supported in this implementation.
+The
+.Nm
+utility accepts the
+.Fl
+option as a synonym for
+.Fl i .
.Sh SEE ALSO
+.Xr printenv 1 ,
+.Xr sh 1 ,
.Xr execvp 3 ,
.Xr environ 7
.Sh STANDARDS
The
.Nm
utility conforms to
-.St -p1003.2-92 .
+.St -p1003.1-2001 .
+The
+.Fl P , S , u
+and
+.Fl v
+options are non-standard extensions supported by
+.Fx ,
+but which may not be available on other operating systems.
+.Sh HISTORY
+The
+.Nm
+command appeared in
+.Bx 4.4 .
+The
+.Fl P , S
+and
+.Fl v
+options were added in
+.Fx 6.0 .
.Sh BUGS
+The
+.Nm
+utility does not handle values of
+.Ar utility
+which have an equals sign
+.Pq Ql =
+in their name, for obvious reasons.
+.Pp
+The
.Nm
-doesn't handle commands with equal
-.Pq Dq =
-signs in their
-names, for obvious reasons.
+utility does not take multibyte characters into account when
+processing the
+.Fl S
+option, which may lead to incorrect results in some locales.
projects / apple / shell_cmds.git / blobdiff