gsettings: command not found

Question

I am trying to create a script, which will change the wallpaper automatically when run.

#!/bin/bash

cd ~/
rm -r ~/.wallpaper
mkdir .wallpaper
cd ~/.wallpaper

wget https://source.unsplash.com/random/1920x1080
USER=$(whoami)
PATH="file:///home/$USER/.wallpaper/1920x1080"
echo $PATH
gsettings set org.gnome.desktop.background picture-uri "$PATH"

But when i do ./change_wallpaper.sh I get the echo correctly, but then

./change_wallpaper.sh: line 12: gsettings: command not found

However, when I run the same command from terminal, it executes fine and wallpaper is getting changed.

When I run whereis gsettings it tells

gsettings: /usr/bin/gsettings /usr/share/man/man1/gsettings.1.gz

Why is it showing gsettings: command not found when I execute from script?

Answer 1

Because you change the PATH in your script. This reserved variable is used to locate executable files. Use another variable.

Same with USER: it is reserved as well and already contains the current user, i.e. you do not need to set USER=$(whoami).

In general, when creating variables in shell scripts it is a good idea to use lowercase names. Usually, predefined variables (like HOME, USER, PATH) are all UPPERCASE and a simple way to avoid overwriting them is to use lowercase names in own scripts. Or use some prefix, e.g. MY_PATH, MY_USER etc.

Answer 2

Your script won't work for everyone. The variable you set for home for your user will be incorrect for people who have their HOME location in a different place from /home/user. For instance, my home location for my personal space is /home/user/l/j/ljames.

Instead of setting the path to be "file:///home/$USER/.wallpaper/1920x1080" you should more correctly change it to "file:///$HOME/.wallpaper/1920x1080". The variable $HOME is already expanded to the full home space of the user.

Your script will work if with these changes:

#!/bin/bash

cd ~/
rm -r ~/.wallpaper
mkdir .wallpaper
cd ~/.wallpaper

wget https://source.unsplash.com/random/1920x1080
# USER=$(whoami) This line isn't neccesary.)    
path="file:///$HOME/.wallpaper/1920x1080"
echo $path
gsettings set org.gnome.desktop.background picture-uri "$path"

A more efficient example is:

#!/bin/bash

[ ! -d ~/.wallpaper ] && mkdir ~/.wallpaper
cd ~/.wallpaper
wget -O 1920x1080 https://source.unsplash.com/random/
path="file:///$HOME/.wallpaper/1920x1080"
rm ~/.cache/wallpaper/*
gsettings set org.gnome.desktop.background picture-uri "$path"

The explaining of the lines are:

Line #1:  Create wallpaper directory if it doesn't exist.
Line #2:  Move to the folder.
Line #3:  Overwrite the current file with the new wallpaper.
Line #4:  Set the pathname variable.
Line #5:  Removed the Wallpaper cache for image change detection.
Line #6:  Active the new wallpaper.