We have discussed on previous post about the rc.local file, This file used for run the scripts or services when your system boot time,

For example would you like to run the Shell scripts or any other services on system booting time just add that line in rc.local file.

I would like to add the below service,

/usr/local/sbin/linuxfaq -c /etc/linuxfaq/linuxfaq.conf

You need to check the file permission whether executable format?

#  ls -l /etc/rc.local
-rwxr-xr-x 1 root root 364 Nov 11 23:56 /etc/rc.local

Open that file using text editor and add a line
# vim /etc/rc.local

#!/bin/sh -e
# rc.local
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
# In order to enable or disable this script just change the execution
# bits.
# By default this script does nothing.

/usr/local/sbin/linuxfaq -c /etc/linuxfaq/linuxfaq.conf

exit 0

Finally, save the file.