Create a self-contained installer in Bash

12 Feb 2015 Matteo Mattei linux bash installer

In this post I will show you how to develop a self contained Linux command line installer in Bash that will decompress an archive and perform some tasks.

Installer content

Our installer that is basically a self-extracting archive with some logic around, consists in three parts:

• A bash script that performs the extraction of the archive and applies some logic.
• A marker to separate the bash script and the archive.
• An archive containing the actual data to install.

Start now!

Create a new bash script called installer.sh with the following content:

#!/bin/bash

echo ""
echo "My Command Line Installer"
echo ""

# Create destination folder
DESTINATION="/opt/my_application"
mkdir -p ${DESTINATION}

# Find __ARCHIVE__ maker, read archive content and decompress it
ARCHIVE=$(awk '/^__ARCHIVE__/ {print NR + 1; exit 0; }' "${0}")
tail -n+${ARCHIVE} "${0}" | tar xpJv -C ${DESTINATION}

# Put your logic here (if you need)

echo ""
echo "Installation complete."
echo ""

# Exit from the script with success (0)
exit 0

__ARCHIVE__

This script is self-explain but I will try to describe the steps:

1. Create a destination folder ${DESTINATION}.
2. Find __ARCHIVE__ marker and put the tarball content into ${ARCHIVE} variable.
3. Decompress the tarball into the destination folder.
4. Eventually apply your installation logic (copy some files, change some others, etc…).
5. Exit from the script (this step is mandatory otherwise bash will try to interpret the tarball and will exit with error).
6. Add __ARCHIVE__ marker at the bottom of the script. This marker will be used to separate the actual bash script with the tarball content.

Now generate a compressed tarball of your application (I used .tar.xz in the above example):

tar cJf myarchive.tar.xz /folder/to/archive

OK, now append it to the installer bash script and make it executable:

cat myarchive.tar.xz >> installer.sh
chmod +x installer.sh

That’s all! You can now distribute your installer.

Execute your installer

The users will execute your installer simply running:

./installer.sh