Updated: 2021/Apr/14

APPLY(1)                    General Commands Manual                   APPLY(1)

     apply - apply a command to a list of arguments

     apply [-ac] [-#] command arguments ...

     apply divides its arguments into fixed-size groups and runs command in
     turn on each group.

     On each execution of command, each character sequence of the form "%d" in
     command, where d is a digit from 1 to 9, is replaced with the d'th
     argument from the current argument group.  The argument group size is set
     to the largest such d found.  Any given argument number can be used
     arbitrarily many times.  (Including zero.)

     If no explicit substitution sequences are found in command, the current
     argument group is substituted after command delimited by spaces, and the
     argument group size defaults to 1 and can be set with the -# option.

     If the argument group size is set to 0, one argument from arguments is
     taken for each execution of command anyway, but is discarded and not
     substituted; thus, command is run verbatim once for every argument.

     The options are as follows:

     -#   Set the argument group size.  Ignored if explicit substitutions are

     -ac  Change the magic substitution character from the default "%" to c.

     The following environment variable affects the execution of apply:

     SHELL  Pathname of the shell to use to execute command.  If this variable
            is not defined, the Bourne shell is used.

     /bin/sh  Default shell.

     apply echo *
            Prints the name of every file in the current directory.
     apply -2 diff a1 b1 a2 b2 a3 b3
            Compares the `a' files to the `b' files.
     apply -0 who 1 2 3 4 5
            Runs who(1) 5 times.
     apply 'ln %1 /home/joe/joe.%1' *
            Hard-links all files in the current directory into the directory
            /home/joe, with their names prefixed with "joe.".
     apply 'cvs diff %1 > %1.diff' *.c
            Diff all C sources in the current directory against the last
            checked-in version and store each result in its own output file.

     The apply command appeared in 4.2BSD.

     Rob Pike

     The complete command to be executed on each iteration is assembled as a
     string without additional quoting and then passed to a copy of the shell
     for parsing and execution.  Thus, commands or arguments that contain
     spaces or shell metacharacters may behave in unexpected ways.

     To protect a shell metacharacter fully it must be quoted twice, once
     against the current shell and once against the subshell used for
     execution.  Similarly, for a shell metacharacter to be interpreted by the
     subshell it must be quoted to protect it from the current shell.  A
     simple rule of thumb is to enclose the entire command in single quotes
     ('') so that the current shell does not interpret any of it.

     There is no easy way to produce the literal string "%1" in command.

     apply unconditionally inserts "exec" at the beginning of each copy of
     command so compound commands may not behave as intended.

NetBSD 9.99                     March 12, 2016                     NetBSD 9.99