for — Apollo

10.0;for, revision 1.0, 88/01/21
for -- Execute a for statement.
usage: for var_name := int_expr [to int_expr] [by int_expr] command... endfor
for var_name in string_expr [by {char|word|line}]    command... endfor



NAME
     for - execute a for statement

SYNOPSIS
     for var_name := int_expr [to int_expr] [by int_expr] command... endfor
     for var_name in string_expr [by {char|word|line}]  command... endfor

DESCRIPTION
     for allows you to build a control structure that executes commands
     repeatedly as long as the result of a Boolean test is true.  The for
     command has two formats: one for assigning and testing integer
     expressions; the other for assigning and testing string expressions.

     In the integer form, the (optional) to and by clauses permit you to
     specify ranges and increment values, respectively.  For example, you
     might want to loop five times by specifying

     for a := 0 to 10 by 2

     If you do not specify by int_expr, the default increment is 1.  If you do
     not specify to int_expr, you probably want to increment the variable
     manually inside the body of the loop.  You should also put a test
     condition inside the loop (and probably use an exit to get out) or you
     risk looping forever.

     In the string form, the (optional) by clause allows you to control the
     string assignment operation.  If you specify by word (the default), each
     word (a sequence of non-blank characters) in string_expr is assigned to
     var_name one at a time until string_expr is exhausted.  You may also
     assign string values a character at a time, or a line at a time, by using
     the by char and by line clauses, respectively.

ARGUMENTS
     var_name (required)
                     Specify the name of the shell variable whose value is to
                     be assigned and tested.

     int_expr (required)
                     Specify any valid expression that returns an integer
                     value.

     string_expr (required)
                     Specify any valid expression that returns a string value.

     command... (required)
                     Specify the command to be executed as long as the for
                     test returns true.  This may be a shell command, a shell
                     script, a variable assignment, or any other valid shell
                     operation.  Multiple commands are permitted; separate
                     them with semicolons or newline characters.

EXAMPLES
     The following example demonstrates the advantages of a for loop over a
     while loop in one instance.  Assume these lines appear in a shell script.

     # A loop using while.
     eon
     a := 0
     while ((^a <= 10)) do
           args ^a
           a := ^a + 2
     enddo
     #
     # The same loop using for.
     #
     for a := 0 to 10 by 2
           args ^a
     endfor
     #
     # End of script.

     This example assigns three names to a variable.

     #
     # Script file_name
     #
     eon
     for file in "foo bar zap" by word
         args ^file
     endfor
     #
     # end of script.

     Execution produces this:

     $ file_name
       foo
       bar
       zap
     $
Museum
