**fScan Reference Manual, Chapter 2 (CmdLineOptions): if**
===== If -- Test some condition before executing commands =====
**usage:** -if EXPR { COMMANDS }\\
**or:** -if ! EXPR { COMMANDS }
===== =====
  *EXPR -This argument to IF must be an expression that will yield a numerical value.

If EXPR > 0, the COMMANDS string inside the curly brackets will be executed next.\\
Otherwise, the COMMANDS string will be ignored.

EXPR can be a single number, an arithmetic expression, or a [[jvs:fscan:manual:chapter1:status|status query]]. The EXPR argument must not contain any spaces within it. Examples of valid EXPR arguments are:
  $xdim                - data set image width
  ?taskname            - query whether the TASKNAME variable is set for the current data set
  $zdim-30             - true if there more than 30 slices (ZDIM)
  exists(param.tmp)    - true if file "param.tmp" exists

If '!' appears before the EXPR argument, the IF condition is true if EXPR is 0.\\
Note: the '!' must be separated from IF and EXPR by spaces.

**See Also:**\\
[[jvs:fscan|fScan Home]], 
[[jvs:fscan:manual|fScan Manual]], 
[[jvs:fscan:manual:chapter2|CmdLineOptions]], 
[[jvs:fscan:manual:help|Manual Help]]