sed_substitute.sh

#!/bin/bash

# Copyright © 2022 Benoît Boudaud <https://miamondo.org/contact/>
# 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 3 of the License, or 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, see <http://www.gnu.org/licenses/>

# This code replaces a string by using the sed command. In the example below, I browse all launcher
# files in the /usr/share/applications directory looking for the string "Exec=firefox http"
# which I replace with "Exec=vivaldi-stable http."

directory=/usr/share/applications

for app in `ls "$directory"`
do
    if ! [[ -d "$app" ]]
    then
        sed -i 's/Exec=firefox http/Exec=vivaldi-stable http/g' $directory/$app
    fi
done

# -------------------------------------------------------------------------------------------------

# it is possible to pass three parameters to the script (Directory, replaced text, new text) So the
# command would be:

#    sed_substitute.sh /usr/share/applications Exec=firefox http Exec=vivaldi-stable http

# And the code should be:

# for app in `ls $1`
# do
#    if ! [[ -d "$app" ]]
#    then
#        sed -i "s/$2/$3/g" $1/$app
#    fi
# done

# line 39 : Take care of double quoting the sed expression. You have to do so, if this one contains
# variables. Otherwise, it doesn't work.