The ` program

` runs a program and stores its output in an environment variable, then executes another program.

Interface

In an execlineb script:

     ` [ -i | -I | -D default ] [ -n ] variable { prog1... } prog2...

` reads prog1... in a block and unquotes it.
It runs prog1... as a child process and saves its output in memory. This output must not contain a null character.
` execs into prog2..., with variable added to the environment with prog1...'s output as a value.

Options

-n : chomp an ending newline off prog1...'s output.

The other options tell ` what to do if prog1...'s output is not suitable as the contents of an environment variable (i.e. it contains a null character) or if prog1... crashes or exits nonzero:

-i : ` exits 1.
-I : variable is removed from the environment, and execution proceeds.
-D default : the value of variable is set to default, and execution proceeds.
neither of those options: the value of variable is set to whatever the start of prog1...'s output is, up to the first null character, or to whatever prog1... wrote before crashing; then execution proceeds.

Notes

You can start prog2... with "$ -u variable variable" to perform variable substitution.