Just wanted to share an alias I have in use and found it useful again. It’s a simple wrapper around xargs, which I always forget how to use properly, so I set up an alias for. All it does is operate on each line on stdout.
The arguments are interpreted as the command to execute. The only thing to remember is using the {} as a placeholder for the input line. Look in the examples to understand how its used.
# Pipe each line and execute a command. The "{}" will be replaced by the line.
#
# Example:
# cat url.txt | foreach echo download {} to directory
# ls -1 | foreach echo {}
# find . -maxdepth 2 -type f -name 'M*' | foreach grep "USB" {}
alias foreach='xargs -d "\n" -I{}'
Useful for quickly operating on each line of a file (in example to download from list of urls) or do something with any stdout output line by line. Without remembering or typing a for loop in terminal.
I recommend you gnu parallel. It does similar things, but runs the commands in parallel. And it’s way easier to pipe than xargs. If you really need it to run one command at a time you can give number of cores to 1. And it also has progress bars, colors to differentiate stdout fo different commands, etc.
Basic example: to echo each line
parallel echo < somefile.txt
To download all links, number of jobs 4, show progress
parallel -j 4 --bar ''curl -O" < links.txtYou can do lot more stuffs with inputs, like placing them wherever with
{}, numbers ({1}is first) that allow multiple unique arguments, transformers like remove extension, remove parent path, etc. worth learningI am actually aware of parallel and use it for a different tool / script I built. The purpose of parallel is different than xargs, right? I mean xargs works on each line of a stdout string, which is what I was using it for. I never thought parallel as an alternative to xargs and need to investigate into this idea more. Thanks.