Continue an SFK script at a different point, or stop the script due to a condition with sfk if.
sfk ... +if [opts] expression command1 ... +command2sfk ... +if expr [+]begin +cmd1a +cmd1b ... +endif +cmd2
execute command1 if expression is true, then continue to command2.
if expression is not true, skip directly to command2.
can be used only in a command chain, after another command.
use "+if expr +begin ... +endif" to run multiple commands
as one block, if expression is true.
supported expressionsreturn code comparison
"rc=n" return code of previous command equal to n
"rc>n" return code of previous command higher than n
"rc<n" return code of previous command lower than n
"rc<>n" return code of previous comm. not equal to n
generic text or number comparison
"l = r" left part is equal to right
"l <> r" left part is not equal to right
"l < r" left part is lower then right
"l > r" left part is higher then right
"l <= r" left part is lower or equal
"l >= r" left part is higher or equal
if both l and r contain only digits a numeric
comparison is done, else a text comparison.
options for if must be given before expression.
-var use sfk variables, must be first option.
-text force text comparison (nocase)
-case case sensitive text comparison
-debug tell what is done in a generic comparison
since sfk 1.7.7 this command no longer consumes
text input from the command chain.
see alsosfk call call sub functions in a script.
sfk goto jump to a local label.
examplessfk filter in.txt -+err +if "rc>0" run -yes "x.bat" +echo done
if file in.txt contains the word "err", run x.bat.
the "echo done" is always executed.
sfk xex -justrc in.txt "/foo*bar/"+if "rc=0" stop 9 "[Red]error:[def] miss" +echo "match"
type this all in one line, or use "sfk cmd 18". 
if file in.txt does not contain the search pattern
then stop with return code 9, printing an error.