How do I pipe a newline separated list as arguments to another command?

Use xargs:

mycommand | xargs -L1 id

Example:

$ (echo root; echo nobody) | xargs -L1 id
uid=0(root) gid=0(root) groups=0(root)
uid=65534(nobody) gid=65534(nogroup) groups=65534(nogroup)

You can also loop over the input in bash:

mycommand | while read line
do
    id "$line"
done

xargs converts input to arguments of a command. The -L1 option tells xargs to use each line as a sole argument to an invocation of the command.

With bash, you can capture the lines of output into an array:

mapfile -t lines < <(mycommand)

And then iterate over them

for line in "${lines[@]}"; do
    id "$line"
done

This is not as concise as xargs, but if you need the lines for more than one thing, it's pretty useful.

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