IF

Evaluates conditional operations in script files.

Format

IF [NOT] [WARN | ERROR | FAIL] [<string> EQ| GT | GE <string>] [VAL] [EXISTS
<filename>]

Template

NOT/S,WARN/S,ERROR/S,FAIL/S,EQ/K,GT/K,GE/K,VAL/S,EXISTS/K

Location

Internal

In a script file, IF, when its conditional is true, carries out all the
subsequent commands until an ENDIF or ELSE command is found. IF must be used
in conjunction with ENDIF, however, ELSE is optional. When the conditional is
not true, execution skips directly to the ENDIF or to an ELSE. The conditions
and commands in IF and ELSE blocks can span more than one line before their
corresponding ENDIFs.

Nested Ifs jump to the matching ENDIF.

The additional keywords are as follows:

NOT

Reverses the interpretation of the result.

WARN

True if previous return code is greater than or equal to 5.

ERROR

True if previous return codes is greater than or equal to 10; only available
if FAILAT is set to greater than 10.

FAIL

True if previous return code is greater than or equal to 20; only available
if FAILAT is set to greater than 20.

<a> GT <b>

True if the test of a is greater than the text of b (disregarding case). Use
NOT GT for less than.

<a> GE <b>

True if the text of a is greater than or equal to the text of b (disregarding
case). Use NOT GE for less than or equal to.

<a> EQ <b>

True if the text of a and b is identical (disregarding case).

VAL

Specifies a numeric comparison.

EXISTS <file>

True if the file exists.

If more than one of the three condition-flag keywords (WARN, ERROR, FAIL) are
given, the one with the lowest value is used.

You can use local or global variables with IF by prefacing the variable name
with a $ character.

Example 1:

IF EXISTS Work/Prog
TYPE Work/Prog HEX
ELSE
ECHO "It's not here"
ENDIF

AmigaDOS displays the file Work/Prog if it exists in the current directory.
Otherwise, AmigaDOS displays the message It's not here and continues after
the ENDIF.

Example 2:

IF ERROR
SKIP errlab
ENDIF
ECHO "No error"
LAB errlab

If the previous command produces a return code greater than or equal to 10,
AmigaDOS skips over the ECHO command to the errlab label.

See also: EXECUTE, FAILAT, LAB, QUIET, SKIP. For more examples using the IF
command, see Chapter 8.