How do I set another search directory for wallpapers?

* EDIT - Second try - and apologies immediately for all the terminal work - hopefully this should just be copying and pasting the highlighted entries*

the folder that holds the details of the gnome wallpapers is called /usr/share/gnome-background-properties/ubuntu-wallpapers.xml

You could edit that file to have wallpaper.../wallpaper sub-sections pointing to your new folder & wallpaper files

Below is a script amended from this forum entry which will regenerate the ubuntu-wallpapers.xml file automatically for a folder containing .png and .jpg files.

copy and paste the contents into a new text file called "ubuntu-wallpaper-generator"

Then execute the file with the syntax

sh ubuntu-wallpaper-generator <path to new wallpaper folder>

This will generate a file called ubuntu-wallpapers.xml in the same folder as where you are running this script.

Safely backup you current xml file i.e.

sudo cp /usr/share/gnome-background-properties/ubuntu-wallpapers.xml /usr/share/gnome-background-properties/ubuntu-wallpapers.xml.backup

the copy in the newly generated file

sudo cp ubuntu-wallpapers.xml /usr/share/gnome-background-properties/ubuntu-wallpapers.xml

Here is that script file I referred to:

#!/bin/bash
#
# This script will take all wallpapers in a given folder and
# make them available as "default" background in the "Change Background" gui
# frontend in Ubuntu.
#
################################################################################

#CONFIG_DIR="/usr/share/gnome-background-properties"
CONFIG_DIR="./"
XML_FILE="$CONFIG_DIR/ubuntu-wallpapers.xml"

if [ $# -ne 1 ]; then
   echo "*** syntax ubuntu-wallpaper-generator <path to wallpaper folder> ***"
   echo "*** for example ***"
   echo "*** ubuntu-wallpaper-generator /usr/share/backgrounds ***"
   exit 1
else
   WALLPAPER_DIR=$1
   echo "*** parameters passed: $1 ***"
fi

#### First check if we have write permissions to the share dirctory. ####
touch $CONFIG_DIR/testfile >/dev/null 2>/dev/null
if [ $? -ne 0 ]; then
   echo "**** No permissions to the desktop share directory. ****"
   echo "**** $CONFIG_DIR ****"
   echo "**** Procedure Terminated. ****"
   exit 1
else
   rm $CONFIG_DIR/testfile 2>/dev/null
fi

#### Show the script description message. ###
cat <<EOF

################################################################################
     This script makes all pictures in the $WALLPAPER_DIR
     directory available to all users defined on this system as their
     system-wide GNOME wallpapers.
################################################################################
EOF

#### Fail if the wallpaper directory does not exist. ####
if [ ! -d $WALLPAPER_DIR ]; then
    echo "**** The wallpaper directory \"$WALLPAPER_DIR\" does not exist. ****"
    echo "**** Precedure Terminated. ****"
    exit 1
fi

#### Count the number of jpg/jpeg/png images. ####
numfiles=`ls -1 $WALLPAPER_DIR/*.jpg WALLPAPER_DIR/*.jpeg WALLPAPER_DIR/*.png 2>/dev/null | wc -l`

#### If there are no image files there then exit. ####
if [ $numfiles -eq 0 ]; then
    echo "**** The wallpaper directory \"$WALLPAPER_DIR\" has no images. ****"
    echo "**** Precedure Terminated. ****"
    exit 1
fi

#### Now we create the XML file containing the images for backgrounds. ####
#### Start by creating the header in the XML file. ####
cat <<EOF > $XML_FILE
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE wallpapers SYSTEM "gnome-wp-list.dtd">
<wallpapers>
EOF

#### Add each file to the XML file. ####
#### Doing it this way makes sure files with spaces in their names are ####
#### handled properly.   (ls .... | while read fname; do)              ####
ls -1 $WALLPAPER_DIR/*.jpg $WALLPAPER_DIR/*.png $WALLPAPER_DIR/*.jpeg 2> /dev/null |
while read image_name; do
   echo "   Adding: `basename "$image_name"`."
   fname=`basename "$image_name"`
   fname="${fname%%\.*}"
   echo "  <wallpaper>"                          >> $XML_FILE
   echo "    <name>$fname</name>"                >> $XML_FILE
   echo "    <filename>$image_name</filename>"   >> $XML_FILE
   echo "    <options>stretched</options>"       >> $XML_FILE
   echo "    <pcolor>#c58357</pcolor>"           >> $XML_FILE
   echo "    <scolor>#c58357</scolor>"           >> $XML_FILE
   echo "    <shade_type>solid</shade_type>"     >> $XML_FILE
   echo "  </wallpaper>"                         >> $XML_FILE
done

#### Create the footer for the XML file. ####
echo "</wallpapers>"                             >> $XML_FILE

cat <<EOF
################################################################################
     You're almost done. copy the generated file ubuntu-wallpapers.xml to the
     folder /usr/shared/gnome-background-properties
     REMEMBER to backup the current ubuntu-wallpaper.xml in that folder first!
################################################################################

EOF

With CreBS (Create Background Slideshow) you can create the XML files for wallpaper slideshows -- the fullpaths to the images are stored in the XML so no moving of files needed.

https://launchpad.net/crebs

http://www.obfuscatepenguin.net/crebs/

heres an update:

    #!/bin/bash

    ################################################################################
    # This script will take all wallpapers in a given folder and
    # make them available as options in the "change desktop background" OR "system->pref->apperances"
    # dialog boxes.
    # for ubuntu or debian
    #    wallpapers are in /usr/share/pixmaps/backgrounds/gnome OR /usr/share/backgrounds
    #    config file(s) for the dialog are in /usr/share/gnome-background-properties
    # --that will make them system wide. 
    #
    #ToDo:
    #  paths with spaces.
    ################################################################################

    # put the output in the same directory as this script
    OutDirectory="$( cd "$( dirname "$0" )" && pwd )"
    OutFile="$OutDirectory/gnome-added.xml"

    # options
    options="zoom"      #zoom is best but stretch,center,scale,tile,span
    shade_type="solid"  #horizontal-gradient, vertical-gradient    
    pcolor="#000000"
    scolor="#000000"


    if [ $# -ne 1 ]; then
       echo "*** need path to directory containing files to include."
       echo "*** for example:     /usr/share/backgrounds"
       exit 1
    else
       ScanDirectory=$1
    fi

    #------need to strip and trailing "/" or this writes incorrect file names.
    # not if [ "$lastchr" -eq "/" ]
    # lastchr=`expr substr $ScanDirectory ${#ScanDirectory} 1`  #--OR:
    lastchr=${ScanDirectory#${ScanDirectory%?}}
    if [ "${lastchr}" = "/" ]; then
       ScanDirectory=${ScanDirectory%?}
    fi
    #--operating in same directory as the script? set full path for the xml file
    if [ ${#ScanDirectory} -le 1 ]; then
            ScanDirectory=$OutDirectory
    fi

    # ---does directory exist
    if [ ! -d $ScanDirectory ]; then
        echo "**** The wallpaper directory \"$ScanDirectory\" does not exist. ****"
        echo "**** Precedure Terminated. ****"
        exit 1
    fi
    # ----can we write to it?
    # touch $OutDirectory/testfile >/dev/null 2>/dev/null
    # if [ $? -ne 0 ]; then
    if [ ! -w $OutDirectory ]; then
       echo "**** No permissions to the desktop share directory. ****"
       echo "**** $OutDirectory ****"
       echo "**** Procedure Terminated. ****"
       exit 1
    fi


    #### Count the number of jpg/jpeg/png/svg [tif(f)] images. ####
    numfiles=`ls -1 $ScanDirectory/*.jpg ScanDirectory/*.jpeg ScanDirectory/*.png ScanDirectory/*.svg 2>/dev/null | wc -l`

    #### If there are no image files there then exit. ####
    if [ $numfiles -eq 0 ]; then
        echo "**** The wallpaper directory \"$ScanDirectory\" has no images. ****"
        echo "**** Precedure Terminated. ****"
        exit 1
    fi

    #### Now we create the XML file containing the images for backgrounds. ####
    #### Start by creating the header in the XML file. ####
    cat <<EOF > $OutFile
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE wallpapers SYSTEM "gnome-wp-list.dtd">
    <wallpapers>
    EOF

    #### Add each file to the XML file. ####
    #### Doing it this way makes sure files with spaces in their names are ####
    #### handled properly.   (ls .... | while read fname; do)              ####
    ls -1 $ScanDirectory/*.jpg $ScanDirectory/*.png $ScanDirectory/*.jpeg $ScanDirectory/*.svg 2> /dev/null |
    while read image_name; do
       fname=`basename "$image_name"`
       echo "   Adding: $fname."

       echo "  <wallpaper deleted=\"false\">"          >> $OutFile
       echo "    <name>$fname</name>"                >> $OutFile
       echo "    <filename>$image_name</filename>"   >> $OutFile
       echo "      <options>$options</options>"       >> $OutFile
       echo "      <pcolor>$pcolor</pcolor>"           >> $OutFile
       echo "      <scolor>$scolor</scolor>"           >> $OutFile
       echo "      <shade_type>$shade_type</shade_type>"     >> $OutFile
       echo "  </wallpaper>"                         >> $OutFile
    done

    #### Create the footer for the XML file. ####
    echo "</wallpapers>"                             >> $OutFile

I faced the same problem, and I wrote a python script to edit a custom xml file that can be placed in /usr/share/gnome-background-properties/my-backgrounds.xml. It's on GitHub.

Example usage:

To add space_galaxy.jpeg and fuzz_dog.png to the xml file:

python my-backgrounds.py -a space_galaxy.jpeg fuzzy_dog.png -n "Cool Galaxy" "Cute Dog"

Note that the default xml file is at /usr/share/gnome-background-properties/my-backgrounds.xml (this is where GNOME watches for the xml's). To specify an alternative xml file, use the -x option:

python my-backgrounds.py -a space_galaxy.jpeg -x ~/my-backgrounds.xml

To remove entries from the xml file use the -r option:

python my-backgrounds.py -r "Cool Galaxy" fuzzy_dog.png

This works with GNOME 3.6 and Python 3.3

This is how I do it.

1. Right click on the Desktop > Change Background.

2. Click Add on the Background Tab.

3. Go into the folder, and select all the wallpapers, by clicking on one, and pressing Ctrl + A.

They should be now displayed in the chooser. I am also trying to find a small app that I had used, to automatically change the wallpaper. Ill post when I find it.

I found one called Wally, and its highly recommended, but I remember I hadnt used that one. Anyway, you can install it by typing

sudo apt-get install wally

in a terminal.

To show the wallpapers in the selector, without having to manually update the folder, you will have to add them to /usr/share/backgrounds.

I also was able to list the wallpapers in the chooser, by creating a symlink in the folder.

$ cd /usr/share/backgrounds
$ ln -s /path/to/wallpapers

That might be helpful, because it may not always be convinient to add wallpapers to a folder owned by root everytime.