z/OS V1R9.0 UNIX System Services Command ... - Christian Grothoff

comm
Portability
Related Information
cmp, diff, sort, uniq
Incorrect command-line options are reported but do not affect the exit status value.
POSIX.2, X/Open Portability Guide, UNIX systems.
command — Run a simple command
Format
Description
Options
Example
command [–p] command-name [argument...]
command [–V|–v] command-name
command causes the shell to suppress its function lookup and execute the given
command-name and arguments as though they made up a standard command line.
In most cases, if command-name is not the name of a function, the results are the
same as omitting command. If, however, command-name is a special built-in
command, (see sh), some unique properties of special built-in commands do not
apply:
v A syntax error in the command does not cause the shell running the command to
stop.
v Variable assignments specified with the special built-in command do not remain
in effect after the shell has run the command.
–p Searches for command-name using the system default PATH variable.
–v Writes a string indicating the pathname or command that the shell uses to
invoke command-name.
–V Writes a string indicating how the shell interprets command-name. If
command-name is a command, a regular built-in command, or an
implementation-provided function found using the PATH variable, the string
identifies it as such and includes the absolute pathname. If command-name
is an alias, function, special built-in command, or reserved word, the string
identifies it as such and includes its definition if it is an alias. If the
command is a tracked alias, the string identifies it as cached.
Typically, you use command when you have a command that may have the same
name as a function. For example, here’s a definition of a cd function that not only
switches to a new directory but also uses lc to list the contents of that directory:
function cd {
command cd $1
lc
}
Inside the function, we use command to get at the real cd. If we didn’t do this, the
cd function would call itself in an infinite recursion.
142 z/OS V1R9.0 UNIX System Services Command Reference