if — Apollo

4.0;if, revision 5.0, 82/10/07
IF -- Execute a conditional statement.
usage:  IF command_1 THEN command_2 [ELSE command_3...] ENDIF


FORMAT

  IF command_1 THEN command_2 ... [ELSE command_3 ...] ENDIF


  IF  executes  a  conditional  statement  depending on the results of a Boolean
  test.  You can extend the  IF  command  over  several  lines  if  you  use  it
  interactively or in a Shell script.  When you use IF interactively, and extend
  the  command  over more than one line, the Shell prompts you for each new line
  of the command with the $_ prompt (refer to the example below).


ARGUMENTS

  command_1
  (required)         Specify a command or program to execute and test for truth,
                     or specify a variable expression  or  Boolean  variable  to
                     test  for  truth.    "Truth" usually means that the command
                     executes successfully (without any  errors),  or  that  the
                     Shell   variable   expression   or   Boolean   is   "true".
                     (Specifically,  this  argument  is  evaluated  TRUE  if  it
                     returns an abort severity level of 0 (zero).)

                     Refer  to  Chapter 3 of the DOMAIN System Command Reference
                     Manual for more information on Shell variables.

  command_2
  (required)         Specify command or program to execute if command_1  returns
                     TRUE.

  command_3
  (optional)          Specify command or program to execute if command_1 returns
                     FALSE (i.e., a severity level greater than zero).


EXAMPLES

    1. $ IF eqs a a
       $_ THEN args "a is a"
       $_ ELSE args "Aristotle was wrong."
       $_ ENDIF
       a is a
       $

    2. $ IF eqs ^2 '-c' THEN pas ^1 ELSE bind ^1.bin library -b ^1 ENDIF

  Example 2 will compile the Pascal module named by the first argument  (^1)  if
  the  second  argument  (^2)  is  '-c'.    Then  it  will  bind the module with
  'library'.  If the second argument is not '-c',  or  if  there  is  no  second
  argument, the command simply binds the module.


RELATED TOPICS

  More information is available.  Type:

  - HELP ABTSEV
    for information about abort severity levels.
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