The forstdin program
forstdin uses its input as loop elements to
run another program.
In an execlineb script:
forstdin [ -E | -e ] [ -p | -o okcodes | -x breakcodes ] [ -N | -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
- -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
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 : no autoimport. This is the default.
- -E : autoimport. Instead of spawning
loop..., spawn importas -ui variable variable
loop.... This substitutes variable into the command
line instead of putting it into the environment.
Other options are similar (in name and functionality) to the switches
passed to control a substitution mechanism,
on purpose; however, forstdin does not call the substitution
mechanism and has its own semantics for those options.
- -N : store the whole line in variable,
including the terminating newline (or other delimiter).
- -n : chomp a terminating delimiter from the line from
stdin before storing it into variable. This is the default.
Note that if chomping is active, and the last line of stdin is not
terminated by a delimiter, then this last line will not be processed.
- -C : crunch. If there is an empty line (i.e. that
only contains a delimiter), do not call loop.
- -c : do not crunch, call loop even if
the line is empty. This is the default.
- -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.
- -d delim : use the characters in string
delim as delimiters for a line. Default is "\n", meaning
the input is only split on newlines.
- You can start loop... with "importas -u variable variable"
to perform variable substitution.