Bash String Functions

Ho raccolto una serie di funzioni per manipolare le stringhe in shell script (successivamente ho utilizzato queste funzioni per creare un ulteriore script di generazione password ma questo forse sarà oggetto di un prossimo articolo)

Ecco le funzioni che ho raccolto in questo script:

• calcolare la lunghezza di una stringa
• convertire un carattere ASCII nel corrispondente valore decimale
• convertire un valore decimale nel corrisponde valore ASCII
• convertire una stringa tutta in caratteri maiuscoli
• convertire una stringa tutta in caratteri minuscoli
• cifrare una stringa con ROT1 (come ROT13 ma con un solo shift di carattere)

#!/usr/bin/env bash
# Bash Utility
#
# Copyright (C) 2018 Alessandro Alfonsi
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#

## Examples
#

STRING="Abcdez"
DEC="97"

## Function
#

count_str() {
# count_str() - returns the lentgh of a string
local str="$1"
echo "${#str}"
}

ord() {
# ord() - converts ASCII character to its decimal value
local char="$1"
printf "%d" "'${char}"
}

chr() {
# chr() - converts decimal value to its ASCII character representation
local num="$1"
printf '%b' "$(printf '\%03o' "${num}")"
}

to_upper() {
# to_upper() - returns an uppercase string
local str="$1"
echo "${str}" | tr '[:lower:]' '[:upper:]'
}

to_lower() {
# to_lower() - returns a lowercase string
local str="$1"
echo "${str}" | tr '[:upper:]' '[:lower:]'
}

rot1() {
# rot1() - encrypt a string with rot1
# (replace each letter with the letter 1 position after)
local str="$1"
echo "${str}" | tr 'a-zA-Z' 'b-zaB-ZA'
}

rot13() {
# rot13() - encrypt a string with rot13
# (replace each letter with the letter 13 position after)
local str="$1"
echo "${str}" | tr 'a-zA-Z' 'n-za-mN-ZA-M'
}

## Main
#

FIRST_CHR="${STRING:0:1}"

echo "String: ${STRING}"
echo "String length: $(count_str "${STRING}")"
echo "First character of the string: ${FIRST_CHR}"
echo "Ord of character ${FIRST_CHR}: $(ord "${FIRST_CHR}")"
echo "Chr of number ${DEC}: $(chr "${DEC}")"
echo "Convert a string to uppercase: $(to_upper "${STRING}")"
echo "Convert a string to lowercase: $(to_lower "${STRING}")"
echo "Encrypt a string with ROT1: $(rot1 "${STRING}")"
echo "Encrypt a string with ROT13: $(rot13 "${STRING}")"

# vim: ts=2 sw=2 noet ai nohls

Esecuzione dello script

alex@vegeta ~/stage_git$ ./string-utilities.sh
String: Abcdez
String length: 6
First character of the string: A
Ord of character A: 65
Chr of number 97: a
Convert a string to uppercase: ABCDEZ
Convert a string to lowercase: abcdez
Encrypt a string with ROT1: Bcdefa
Encrypt a string with ROT13: Nopqrm

Alcuni link di riferimento:

Bash String Manipulation Examples – Length, Substring, Find and Replace

Bash string manipulation cheatsheet