Good article to learn redirect

• Bash One-Liners Explained, Part III: All about redirection

Example

• cat nope.txt > output.txt 2>&1 is not the same as cat nope.txt 2>&1 > output.txt

cat nope.txt > output.txt 2>&1

• > output.txt, stdout points to output.txt
• 2>&1, stderr points to stdout and end up pointing to output.txt.
• Everything is written to output.txt.

cat nope.txt 2>&1 > output.txt

• 2>&1, stderr points to stdout which is a terminal
• > output.txt, stdout switches to output.txt but leave stderr still points to a terminal.
• As a result, stderr is written to a terminal but stdout is written to output.txt.

Discard all outputs of a command

• $ command > /dev/null 2>&1 or
• $ command &> /dev/null