Shell Redirections ↔ Quick Guide

File descriptors:

stdin : 0
stdout : 1
stderr : 2

Redirecting `stdin`

This trick can be used to take multi-line input in scripts.

bash

#!/usr/bin/env bash

echo -e "Enter Commit Message (Ctrl+d when done):"
msg=$(</dev/stdin)
echo $msg

Redirecting `stderr`

Use 2>. Compatible with both bash and sh

Redirecting both `stderr` & `stdout`

With bash, use some_command &> /dev/null

With sh,

bash

some_command > where-to-redirect 2>&1
# or
some_command 2>&1 > stdout_and_err

If you want to capture standard output/error separately,
bash
```
$ some_command 1>output.txt 2>error.txt
```