User Commands command(1)
NAME
command - execute a simple command
SYNOPSIS
/usr/bin/command
command [-p] command_name [argument]...
command [-v | -V] command_name
ksh93command [-pvxV] [command_name [argument...]]
DESCRIPTION
The command utility causes the shell to treat the arguments
as a simple command, suppressing the shell function lookup.
If the command_name is the same as the name of one of the
special built-in utilities, the special properties do not
occur. In every other respect, if command_name is not the
name of a function, the effect of command (with no options)
are the same as omitting command.
The command utility also provides information concerning how
a command name is interpreted by the shell. See -v and -V.
ksh93Without the -v or -V option, command executes command_name
with arguments specified by argument, suppressing the shellfunction lookup that normally occurs. In addition, if com-
mand is a special built-in command, the special properties
are removed so that failures do not cause the script that executes it to terminate.If the -v or -V options are specified, command is equivalent
to whence(1). OPTIONSThe following options are supported by /usr/bin/command:
-p Performs the command search using a default value for
PATH that is guaranteed to find all of the standard utilities.-v Writes a string to standard output that indicates the
path or command that is be used by the shell, in the
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User Commands command(1)
current shell execution environment to invokecommand_name, but does not invoke command_name.
o Utilities, regular built-in utilities,
command_names including a slash character,
and any implementation-provided functions
that are found using the PATH variable is written as absolute path names.o Shell functions, special built-in utilities,
regular built-in utilities not associated
with a PATH search, and shell reserved words are written as just their names.o An alias is written as a command line that
represents its alias definition. o Otherwise, no output is written and the exit status reflects that the name was not found.-V Writes a string to standard output that indicates how
the name specified in the command_name operand is
interpreted by the shell, in the current shell execu-
tion environment, but does not invoke command_name.
Although the format of this string is unspecified, it indicates in which of the following categoriescommand_name falls and include the information stated:
o Utilities, regular built-in utilities, and
any implementation-provided functions that
are found using the PATH variable is identi-
fied as such and include the absolute path name in the string.o Other shell functions is identified as func-
tions. o Aliases are identified as aliases and their definitions are included in the string.o Special built-in utilities are identified as
special built-in utilities.
o Regular built-in utilities not associated
with a PATH search is identified as regularbuilt-in utilities.
o Shell reserved words are identified as reserved words.SunOS 5.11 Last change: 8 Apr 2008 2
User Commands command(1)
ksh93The following options are supported by ksh93 command:
-p Causes a default path to be searched rather than the
one defined by the value of PATH.-v Equivalent to:
whence command [argument ...]
-V Equivalent to:
whence -v command [argument ...]
-x If command fails because there are too many arguments,
it is invoked multiple times with a subset of the arguments on each invocation. Arguments that occurprior to the first word that expand to multiple argu-
ments and arguments that occur after the last word that expands to multiple arguments are passed on each invocation. The exit status is the maximum invocation exit status. OPERANDS The following operands are supported: argument One of the strings treated as an argument tocommand_name.
command_name The name of a utility or a special built-in
utility.EXAMPLES
Example 1 Making a Version of cd That Always Prints Out the New Working Directory The following example takes a version of cd that always prints out the new working directory exactly once: cd() {SunOS 5.11 Last change: 8 Apr 2008 3
User Commands command(1)
command cd "$@" >/dev/null
pwd } Example 2 Starting Off a secure shell script in Which the Script Avoids Being Spoofed by Its Parent The following example starts off a secure shell script in which the script avoids being spoofed by its parent: IFS=' '# The preceding value should be
. # Set IFS to its default value.
\unalias -a
# Unset all possible aliases.
# Note that unalias is escaped to prevent an alias
# being used for unalias.
unset -f command
# Ensure command is not a user function.
PATH="$(command -p getconf _CS_PATH):$PATH"
# Put on a reliable PATH prefix.
# ...
At this point, given correct permissions on the directories called by PATH, the script has the ability to ensure that any utility it calls is the intended one. It is being very cautious because it assumes that implementation extensions can be present that would allow user functions to exist when it is invoked. This capability is not specified by this document, but it is not prohibited as an extension. For example, the ENV variable precedes the invocation of the script with a user startup script. Such a script could define functions to spoof the application. ENVIRONMENT VARIABLES See environ(5) for descriptions of the following environmentvariables that affect the execution of command: LANG,
LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.
PATH Determine the search path used during the command
search, except as described under the -p option.
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User Commands command(1)
EXIT STATUS/usr/bin/command
When the -v or -V options are specified, the following exit
values are returned: 0 Successful completion.>0 The command_name could not be found or an error
occurred. Otherwise, the following exit values are returned:126 The utility specified by command_name was found but
could not be invoked.127 An error occurred in the command utility or the util-
ity specified by command_name could not be found.
Otherwise, the exit status of command is that of the simple
command specified by the arguments to command.
ksh93If command is invoked, the exit status of command is that of
command. Otherwise, it is one of the following:
0 command_name completed successfully.
>0 -v or -V has been specified and an error occurred.
126 command_name was found but could not be invoked.
127 command_name could not be found.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:/usr/bin/command
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User Commands command(1)
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcs ||_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| Standard | See standards(5). ||_____________________________|_____________________________|
ksh93____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcsu ||_____________________________|_____________________________|
| Interface Stability | Uncommitted ||_____________________________|_____________________________|
SEE ALSO
ksh93(1), sh(1), type(1), whence(1), attributes(5), environ(5), standards(5)SunOS 5.11 Last change: 8 Apr 2008 6