Bash script tips and tricks

backup-n-delete.sh

#!/bin/sh -x

# Backup and delete files in list file

[ $# -lt 1 ] && { echo "INPUT FILE NAME MISSING!"; exit 1; }
INPUT_FILE=$1

[ -f $INPUT_FILE ] || { echo "INPUT FILE NOT EXIST"; exit 1; }

#Commands
mkdir -pv ~/bakup_`date +%F`

## Back up and remove the in list
for file in $(cat $INPUT_FILE)
do 
    if [ -f $file ]
    then 
        echo $i;
        /bin/cp -vR $file ~/backup_`date +%F`/ --parents;
        /bin/rm -i $file;
    fi
done

Bash-tips-for-everyday-at-the-command-line.sh

#!/usr/bin/env bash
# https://opensource.com/article/18/5/bash-tricks

# History related
ctrl + r (reverse search)
!! (rerun last command)
!* (reuse arguments from previous command)
!$ (use last argument of last command)
shopt -s histappend (allow multiple terminals to write to the history file)
history | awk 'BEGIN {FS="[ \t]+|\\|"} {print $3}' | sort | uniq -c | sort -nr | head (list the most used history commands)

# File and navigation
cp /home/foo/realllylongname.cpp{,-old}
cd -
rename 's/text_to_find/been_renamed/' *.txt
export CDPATH='/var/log:~' (variable is used with the cd built-in.)

# Colourize bash

# enable colors
eval "`dircolors -b`"
# force ls to always use color and type indicators
alias ls='ls -hF --color=auto'
# make the dir command work kinda like in windows (long format)
alias dir='ls --color=auto --format=long'
# make grep highlight results using color
export GREP_OPTIONS='--color=auto'

export LESS_TERMCAP_mb=$'\E[01;31m'
export LESS_TERMCAP_md=$'\E[01;33m'
export LESS_TERMCAP_me=$'\E[0m'
export LESS_TERMCAP_se=$'\E[0m' # end the info box
export LESS_TERMCAP_so=$'\E[01;42;30m' # begin the info box
export LESS_TERMCAP_ue=$'\E[0m'
export LESS_TERMCAP_us=$'\E[01;36m'

# Bash shortcuts
    shopt -s cdspell (corrects typoos)
    ctrl + _ (undo)
    ctrl + arrow (move forward a word)
    ctrl + a (move cursor to start)
    ctrl + e (move cursor to end)
    ctrl + k (cuts everything after the cursor)
    ctrl + l (clears screen)
    ctrl + q (resume command that is in the foreground)
    ctrl + s (pause a long running command in the foreground)
    ctrl + t (swap two characters)
    ctrl + u (cuts everything before the cursor)
    ctrl + x + ctrl + e (opens the command string in an editor so that you can edit it before it runs)
    ctrl + x + * (expand glob/star)
    ctrl + xx (move to the opposite end of the line)
    ctrl + y (pastes from the buffer)
    ctrl + shift + c/v (copy/paste into terminal)

# Running commands in sequence
&& (run second command if the first is successful)
; (run second command regardless of success of first one)

# Redirecting I/O
2>&1 (redirect stdout and stderr to a file)

# check for open ports
echo > /dev/tcp/<server ip>/<port>
`` (use back ticks to shell out)

# Examine executable
which <command>
file <path/to/file>
command -V <some command binary> (tells you whether <some binary> is a built-in, binary or alias)

php-version-change.sh

#!/bin/bash
CURRENT_PHP_VERSION=$(php -r "echo phpversion();"|cut  -c1-3)
NEW_PHP_VERSION=$1

a2dismod php$CURRENT_PHP_VERSION
a2enmod php$NEW_PHP_VERSION
service apache2 restart

update-alternatives --set php /usr/bin/php$NEW_PHP_VERSION
#update-alternatives --set php-fpm /usr/bin/php$NEW_PHP_VERSION-fpm
#update-alternatives --set phar /usr/bin/phar$NEW_PHP_VERSION
#update-alternatives --set phar.phar /usr/bin/phar.phar$NEW_PHP_VERSION
#update-alternatives --set phpize /usr/bin/phpize$NEW_PHP_VERSION
#update-alternatives --set php-config /usr/bin/php-config$NEW_PHP_VERSION

rpf.sh

#!/usr/bin/env bash
#
# Simple rsync profiler
#
# Author: petrberanek.mail@gmail.com (Petr Beranek)
#
# For usage details type `rpf --help'
#

# https://opensource.com/article/20/1/create-save-run-rsync-configurations

set -o errexit
set -o nounset

__name=$(basename "${0}")
__version="0.1"

config_dir="${HOME}/.rpf"
profiles_dir="${config_dir}/profiles"
shared_dir="${config_dir}/shared"
help="\
Usage: ${__name} [OPTION...] PROFILE_NAME

${__name} is simple rsync profiler that stores your different rsync
configurations in named profiles.

Options:
    -c, --create-profile PROFILE_NAME   create new profile (profile data
                            are stored in ${config_dir}/PROFILE_NAME).
                            Profile name can contain alphanumeric
                            characters only.
    -s, --show-profile-config PROFILE_NAME  show content of profile
                            configuration file (stored in
                            ${config_dir}/PROFILE_NAME)
    -l, --list-profiles     list all available profiles
    -h, --help              show this help

Example:
    Create new profile by typing
    ${__name} -c PROFILE_NAME

    edit its config files stored by default in
    ${profiles_dir}/PROFILE_NAME

    and then run it by typing
    ${__name} PROFILE_NAME

    That's it.

${__name} comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to redistribute it under certain conditions. See
the GNU General Public Licence for details.

Email bug reports or enhancement requests to petrberanek.mail@gmail.com.
"


create_profile() {
    # Create dir with given profile name and with default content.
    #
    # Arguments: $1 -- profile name
    #
    # Creates files: conf, exclude
    #
    # If dir with the same name already exists, exits with error.
    #

    local profile_name="${1}"
    local profile_dir="${profiles_dir}/${profile_name}"

    # create default rpf dirs if missing
    if [[ ! -d "${profiles_dir}" ]]; then
        echo "Creating ${profiles_dir}"
        mkdir --parents "${profiles_dir}"
    fi
    if [[ ! -d "${shared_dir}" ]]; then
        echo "Creating ${shared_dir}"
        mkdir --parents "${shared_dir}"
    fi

    # don't overwrite existing profile
    if [[ -d "${profile_dir}" ]]; then
        echo "${__name}: error: profile already exists."
        exit 1
    fi

    echo "Creating ${profile_dir}"
    mkdir "${profile_dir}"

    # create `conf' template
    local conf="${profile_dir}/conf"
    echo "Creating ${conf}"
    cat << EOF > "${conf}"
# rsync config template
#
# Write each rsync option on separate line. For details see man rsync.
# Empty lines and lines starting with # are ignored. Dynamic references
# (e.g. using command substitution) are not supported.
#
# Config files shared between different profiles should be saved in
# ${shared_dir}
#
# Example configuration:
#
--verbose
--archive
--human-readable
# file with patterns of files and directories in source excluded
# from transfer
--exclude-from="${profiles_dir}/${profile_name}/exclude"
--relative
# perform trial run, make no changes
--dry-run
# source, e.g.
${HOME}
# destination, e.g.
/mnt/usb_drive/my_backup
EOF

    # create `exclude' template
    local exclude="${profile_dir}/exclude"
    echo "Creating ${exclude}"
    cat << EOF > "${exclude}"
# \`exclude' template
#
# Lines starting with # or ; are ignored. For details see man rsync,
# section FILTER RULES.
#
EOF

    # all done
    echo "OK"
    echo "Edit profile config files in ${profile_dir} to fit your needs."
}


list_profiles() {
    # Show all available rpf profiles.
    #
    # Assumes that all dirs in $profiles_dir are profiles.
    #

    for item in "${profiles_dir}"/*; do
        if [[ -d "${item}" ]]; then
            basename "${item}"
        fi
    done
}


show_help() { echo "${help}"; }


show_profile_config() {
    # Show configuration file for given profile.
    #
    # Arguments: $1 -- profile name
    #

    local profile_name="${1}"
    less "${profiles_dir}/${profile_name}/conf"
}


check_profile_name() {
    # Check that name is not empty and contains alphanumeric chars only.
    #
    # Arguments: $1 -- profile name
    #
    # If test fails, exits with error.
    #

    if [[ -z "${1}" ]]; then
        echo "${__name}: error: empty profile name."
        exit 1
    elif [[ "${1}" =~ [^a-zA-Z0-9] ]]; then
        echo "${__name}: error: non-alphanumeric characters in profile name."
        exit 1
    fi
}


check_profile_exists() {
    # Check that $profile_name exists and is a directory.
    #
    # Arguments: $1 -- profile name
    #
    # If test fails, exits with error.
    #

    local profile_name="${1}"
    if [[ ! -d "${profiles_dir}/${profile_name}" ]]; then
        echo "${__name}: error: profile ${profile_name} does not exist."
        exit 1
    fi
}


check_num_args() {
    # Check that value of $1 = number of arguments (excluding $1)
    #
    # Arguments: $1 -- limit (positive int)
    #
    # If test fails, exits with error.
    #

    local num_args=$(( ${#} - 1 ))  # do not count $1 in total num of args
    if [[ "${1}" -ne "${num_args}" ]]; then
        echo "${__name}: error: expected num args: ${1}, received: $num_args"
        exit 1
    fi
}


run_rsync() {
    # Run rsync with configuration coresponding to given profile name.
    #
    # Arguments: $1 -- profile name
    #

    local profile_name="${1}"
    local visual_div="=============================="
    local parsed_args
    parsed_args=$(grep --invert-match '^#' "${profiles_dir}/${profile_name}/conf" \
                    | tr '\n' ' ')

    # Print debug info
    echo "${visual_div}"
    echo "${__name} version: ${__version}"
    echo "args: ${parsed_args}"
    echo "${visual_div}"

    # Expand $parsed_args - each item from conf file becomes rsync argument
    # shellcheck disable=SC2086
    rsync ${parsed_args}
}


if [[ "${#}" == 0 ]]; then
    show_help
    exit 1
fi
while [[ "${#}" -gt 0 ]]; do
    case "${1}" in
        -c | --create-profile)
            check_num_args 2 "${@}"
            shift
            check_profile_name "${1:-}" # If $1 is not declared, set it empty.
            create_profile "${1}"
            exit 0;;
        -s | --show-profile-config)
            check_num_args 2 "${@}"
            shift
            check_profile_name "${1:-}"
            check_profile_exists "${1}"
            show_profile_config "${1}"
            exit 0;;
        -l | --list-profiles)
            check_num_args 1 "${@}"
            list_profiles
            exit 0;;
        -h | --help)
            check_num_args 1 "${@}"
            show_help
            exit 0;;
        -*)
            echo "${__name}: error: unknown option \`${1}'"
            exit 1;;
        *)
            check_num_args 1 "${@}"
            check_profile_name "${1:-}"
            check_profile_exists "${1}"
            run_rsync "${1}"
            exit 0;;
    esac
    shift
done