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scripts
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🔍 See Original Answer on Ask Ubuntu ⧉ 🔗
URL:
https://askubuntu.com/q/1102084
Title:
Change dynamic wallpaper directory every season
ID:
/2018/12/15/Change-dynamic-wallpaper-directory-every-season
Created:
December 15, 2018
Edited: January 6, 2022
Upload:
September 15, 2024
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Introduction
The basic question is how to do something at the start of Spring, Summer, Fall and Winter. For this I would create a bash script that runs on boot, rather than clogging up cron with entries.
I’ve approached this answer using the OP’s question “How do I develop a script?”. So I’ve deviated from usual method of simply posting a bash script and enhanced the answer with:
- References are included within the code. They link to Stack Exchange answers for solving specific problems. For example: How to copy files, How to get day of year, etc.
- A section on “Testing” is provided as it is something we all need to do
- A section on “Enhancements” is provided because software is usually developed in versions where each is incrementally better than the previous version.
When do seasons start?
From the Farmer’s Almanac:
Seasons of 2018
| Season | Astronomical Start | Meteorological Start |
|---|---|---|
| SPRING | Tuesday, March 20, 12:15 P.M. EDT | Thursday, March 1 |
| SUMMER | Thursday, June 21, 6:07 A.M. EDT | Friday, June 1 |
| FALL | Saturday, September 22, 9:54 P.M. EDT | Saturday, September 1 |
| WINTER | Friday, December 21, 5:23 P.M. EST | Saturday, December 1 |
Convert season start date to Day of Year
For our bash script to work we need to know what day of the year each seasons start.
$ echo $(date --date="March 20" '+%j')
079
$ echo $(date --date="June 21" '+%j')
172
$ echo $(date --date="Sep 22" '+%j')
265
$ echo $(date --date="Dec 21" '+%j')
355
# Reference: https://unix.stackexchange.com/questions/352176/take-input-arguments-and-pass-them-to-date
## ```
# Create bash script: `season.sh`
Open the terminal using: <kbd>Ctrl</kbd>+<kbd>Alt</kbd>+<kbd>T</kbd>
Create the directory if it doesn't exist: `mkdir -p ~/bin`
Edit the script using: `gedit ~/bin/season.sh`
- **Note:** Lubuntu user's need to use `leafpad` instead of `gedit`
Copy and paste the following lines into `gedit`:
``` bash
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# !/bin/bash
# NAME: season.sh
# PATH: ~/bin
# DATE: December 15, 2018
# NOTE: Written for: https://askubuntu.com/questions/1100934/change-dynamic-wallpaper-directory-every-season/1102084#1102084
# User defined variables, change to suit your needs
# Our directory names, lines indented for cosmetic reasons only
SlideShowDir="~/Season Slide Show"
SpringDir="~/Pictures/Spring Slide Show"
SummerDir="~/Pictures/Summer Slide Show"
FallDir="~/Pictures/Fall Slide Show"
WinterDir="~/Pictures/Winter Slide Show"
CheckTripWire () {
# Our last season is in "~/Season Slide Show/CurrentSeason"
LastSeasonFilename="$SlideShowDir"/CurrentSeason
LastSeason=$(cat "$LastSeasonFilename")
[[ "$LastSeason" == "$Season" ]] && return 0 # Season still the same
# We now know our season has changed.
rm -f "$SlideShowDir"/{*,.*} # Erase all files in target
# Reference: https://askubuntu.com/questions/60228/how-to-remove-all-files-from-a-directory
echo "$Season" > "$LastSeasonFilename" # Record new season in target
# Copy new slide show based on season
if (( "$Season" == SPRING)) ; then
cp -R "$SpringDir"/. "$SlideShowDir"/
# Reference: https://stackoverflow.com/questions/3643848/copy-files-from-one-directory-into-an-existing-directory
elif (( "$Season" == SUMMER)) ; then
cp -R "$SummerDir"/. "$SlideShowDir"/
elif (( "$Season" == FALL)) ; then
cp -R "$FallDir"/. "$SlideShowDir"/
else
cp -R "$WinterDir"/. "$SlideShowDir"/
fi
} # End of CheckTripWire () function.
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# Start of Mainline
DOY=$(date '+%j') # DOY = Current Day of Year
# Reference: https://stackoverflow.com/questions/10112453/how-to-get-day-of-the-year-in-shell
if ((DOY>=079 && DOY<172)) ; then
Season="SPRING" # Spring has sprung!
# Reference: https://stackoverflow.com/questions/12614011/using-case-for-a-range-of-numbers-in-bash
elif ((DOY>=172 && DOY<265)) ; then
Season="SUMMER" # Hit the beach!
elif ((DOY>=265 && DOY<355)) ; then
Season="FALL" # Rake those leaves!
else
Season="WINTER" # Shovel the snow!
fi
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# Current season establish, now see if we tripped the wire
CheckTripWire
exit 0 # Command not necessary but good habit to signify no Abend.
Save the file in gedit. Now mark it as executable using:
chmod a+x ~/bin/season.sh
Next we need to add it to startup applications. Reference: How do I start applications automatically on login?
Note: You probably already have your slide show setup in startup applications. You will want to use season.sh BEFORE your regular slide show as it deletes and copies files which would crash the slide show program if it started first.
Testing
You will want to test season.sh script when you create it and not wait a year to see if it works properly or not. Reference: Faking the date for a specific shell session
Enhancements
After initially developing a script it is common to enhance it Days, Weeks, Months or even Years later. This section discusses some enhancements you might want to make to session.sh down the road.
Compress files to save disk space
Consider keeping the off-season images compressed in TAR (Tape Archive) format to save on disk space. Then replace the cp (Copy) command with the tar command to uncompress the files. Reference: 23 tar Command Examples For Linux:
For example, we would change:
cp -R "$SpringDir"/. "$SlideShowDir"/
To:
tar -xf "$SpringDir"archive.tar -C "$SlideShowDir"/
… and so on for the other seasons.
Setup variables for season start
Using variables for season start days makes it easier to modify the script and makes the code easier to read (aka code readability).
Consider setting up Variables for start of season:
SpringStart=079
SummerStart=179
FallStart=265
WinterStart=355
Define the variables at the top of the script to make them easier to spot and change. You might want to do this for leap years. You might want to change to “Meteorological” season starts instead of “Astronomical” start dates.
Then change these lines:
if ((DOY>=079 && DOY<172)) ; then
elif ((DOY>=172 && DOY<265)) ; then
elif ((DOY>=265 && DOY<355)) ; then
To this:
if ((DOY>="$SpringStart" && DOY<"$SummerStart")) ; then
elif ((DOY>="$SummerStart" && DOY<"$FallStart")) ; then
elif ((DOY>="$FallStart" && DOY<"$WinterStart")) ; then