The `forstdin` program

forstdin uses its input as loop elements to run another program.

Interface

In an execlineb script:

     forstdin [ -p | -o okcodes | -x breakcodes ] [ -E firsteofcode ] [ -e eofcode ] [ -n ] [ -C | -c ] [ -0 | -d delim ] variable loop...

forstdin reads its standard input as it becomes available, splitting it on every line automatically.
For every argument x in the split output, forstdin runs loop... as a child process, with variable=x added to its environment.
forstdin then exits 0 if it has read something on stdin, and 1 if it hasn't read anything.

-p : parallel mode. Do not wait for a loop... instance to finish before spawning the next one. forstdin will still wait for all instances of loop to terminate before exiting, though.
-0 : accept null characters on its stdin, using them as delimiters. If this option and a -d option are used simultaneously, the rightmost one wins.
-o okcodes : okcodes must be a comma-separated list of exit codes. If the -p flag hasn't been given and loop exits with one of the codes in okcodes, forstdin will run the following instances of the loop, but if the exit code is not listed in okcodes, forstdin will exit immediately with an approximation of the same exit code.
-x breakcodes : like the previous option, but with inverted meaning - the listed exit codes are codes that will make forstdin break the loop and exit, and the unlisted exit codes will make it keep looping.
-E firsteofcode : if forstdin encounters EOF on its first attempt to read data, exit firsteofcode. Default is 1.
-e eofcode : if forstdin has already read data, and encounters EOF, exit eofcode. Default is 0.
Other options are used to control the substitution mechanism for every x. Of course, you can't split x. The default delimiter for forstdin is a newline; you need a -d option to split x around other values.

You can start loop... with "importas -u variable variable" to perform variable substitution.