Shell script templates [closed]

Answer 1

Enabling error detection makes it much easier to detect problems in the script early:

set -o errexit

Exit script on first error. That way you avoid continuing on to do something which depended on something earlier in the script, perhaps ending up with some weird system state.

set -o nounset

Treat references to unset variables as errors. Very important to avoid running things like rm -you_know_what "$var/" with an unset $var. If you know that the variable can be unset, and this is a safe situation, you can use ${var-value} to use a different value if it's unset or ${var:-value} to use a different value if it's unset or empty.

set -o noclobber

It's easy to make the mistake of inserting a > where you meant to insert <, and overwrite some file which you meant to read. If you need to clobber a file in your script, you can disable this before the relevant line and enable it again afterwards.

set -o pipefail

Use the first non-zero exit code (if any) of a set of piped command as the exit code of the full set of commands. This makes it easier to debug piped commands.

shopt -s nullglob

Avoid that your /foo/* glob is interpreted literally if there are no files matching that expression.

You can combine all of these in two lines:

set -o errexit -o nounset -o noclobber -o pipefail
shopt -s nullglob

Answer 2

What you can do is to make a script that creates a header for a script & and have it auto open in your favorite editor. I saw a guy do that at this site:

http://code.activestate.com/recipes/577862-bash-script-to-create-a-header-for-bash-scripts/?in=lang-bash

#!/bin/bash -       
#title           :mkscript.sh
#description     :This script will make a header for a bash script.
#author          :your_name_here
#date            :20110831
#version         :0.3    
#usage           :bash mkscript.sh
#notes           :Vim and Emacs are needed to use this script.
#bash_version    :4.1.5(1)-release
#===============================================================================

Answer 3

My bash template is as below(set in my vim configuration):

#!/bin/bash

## DESCRIPTION: 

## AUTHOR: $USER_FULLNAME

declare -r SCRIPT_NAME=$(basename "$BASH_SOURCE" .sh)

## exit the shell(default status code: 1) after printing the message to stderr
bail() {
    echo -ne "$1" >&2
    exit ${2-1}
} 

## help message
declare -r HELP_MSG="Usage: $SCRIPT_NAME [OPTION]... [ARG]...
  -h    display this help and exit
"

## print the usage and exit the shell(default status code: 2)
usage() {
    declare status=2
    if [[ "$1" =~ ^[0-9]+$ ]]; then
        status=$1
        shift
    fi
    bail "${1}$HELP_MSG" $status
}

while getopts ":h" opt; do
    case $opt in
        h)
            usage 0
            ;;
        \?)
            usage "Invalid option: -$OPTARG \n"
            ;;
    esac
done

shift $(($OPTIND - 1))
[[ "$#" -lt 1 ]] && usage "Too few arguments\n"

#==========MAIN CODE BELOW==========