Linux Notes

Last updated on August 8, 2023

apt - Advanced Package Tool

Useful commands for writing shell script

set -e, -u, -o, -x pipefail

`set -e` The set -e option instructs bash to immediately exit if any command [1]
has a non-zero exit status. You wouldn't want to set this for your command-line shell,
but in a script it's massively helpful.

Useful variables

• $@ in Bourne-like shells, in list contexts expands to all the positional parameters as separate arguments. ```shell $> vi script.sh

  script.sh

  #! /bin/sh - exec “$@”

$> script.sh ‘echo’ ‘a b’ ‘x y’

It will call exec with echo, a b, and x y as arguments which will execute echo

(in most sh implementations, /bin/echo as opposed to the echo shell builtin) in the

same process that was previously running the shell interpreting your script with some test and x y as arguments.

```text
command 2> error.log: This redirects StdErr (standard error) of the command to the file error.log. The standard output (StdOut) remains unchanged and continues to be displayed on the terminal.

command 1> out.log: This redirects StdOut (standard output) of the command to the file out.log. The standard error (StdErr) remains unchanged and continues to be displayed on the terminal.

command > error.log: This redirects StdOut (standard output) of the command to the file error.log. However, the standard error (StdErr) is not redirected and continues to be displayed on the terminal.

This is a sapling 🌱 in my digital garden 🏡.

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