Bash Arrays and Iterations

Bash arrays can be great for iterating over a list of items. I’m giving a quick example below on a list of services. All you need is to list all values in different arrays and use an index to map them back together.

Example:

Let’s break down our columns into arrays:

service_arr=(
  CUPS
  MPD
  SSHD
  DHCPD
)

path_arr=(
  /etc/cups
  /etc
  /etc
  /etc
)

config_file_arr=(
  cupsd.conf
  mpd.conf
  sshd.conf
  dhcpd.conf
)

Now to iterate through our items, let’s make sure we start at index 1 and add at each run:

cnt=1

for i in ${!service_arr[@]} ; do
  echo "The configuration file for the service ${service_arr[$i]} is ${path_arr[$i]}/${config_file_arr[$i]}"
  let count+=1
done

The result is:

The configuration file for the service CUPS is /etc/cups/cupsd.conf
The configuration file for the service MPD is /etc/mpd.conf
The configuration file for the service SSHD is /etc/sshd.conf
The configuration file for the service DHCPD is /etc/dhcpd.conf

You can also use especial characters (like * when searching for files and using shell expansion). Just make sure to properly quote them.