doc/usage/cmd/for.rst

   1 .. index::
   2    single: for (command)
   3
   4 for command
   5 ===========
   6
   7 Synopis
   8 -------
   9
  10 ::
  11
  12     for <variable> in <items>; do <commands>; done
  13
  14 Description
  15 -----------
  16
  17 The for command is used to loop over a list of values and execute a series of
  18 commands for each of these.
  19
  20 The counter variable of the loop is a shell variable. Please, keep in mind that
  21 an environment variable takes precedence over a shell variable of the same name.
  22
  23 variable
  24     name of the counter variable
  25
  26 items
  27     space separated item list
  28
  29 commands
  30     commands to execute
  31
  32 Example
  33 -------
  34
  35 ::
  36
  37     => setenv c
  38     => for c in 1 2 3; do echo item ${c}; done
  39     item 1
  40     item 2
  41     item 3
  42     => echo ${c}
  43     3
  44     => setenv c x
  45     => for c in 1 2 3; do echo item ${c}; done
  46     item x
  47     item x
  48     item x
  49     =>
  50
  51 The first line ensures that there is no environment variable *c*. Hence in the
  52 first loop the shell variable *c* is printed.
  53
  54 After defining an environment variable of name *c* it takes precedence over the
  55 shell variable and the environment variable is printed.
  56
  57 Return value
  58 ------------
  59
  60 The return value $? after the done statement is the return value of the last
  61 statement executed in the loop.
  62
  63 ::
  64
  65     => for i in true false; do ${i}; done; echo $?
  66     1
  67     => for i in false true; do ${i}; done; echo $?
  68     0