Many people know about cat command which is useful in displaying entire file content. But in some cases we have to print part of file. In today’s post we will be talking about head and tail commands, which are very useful when you want to view a certain part at the beginning or at the end of a file, specially when you are sure you want to ignore the rest of the file content.
let’s start with the tail command, and explore all of the features this handy command can provide and see how to use it best to suit your needs. After that we will show some options that you can do and can not do with the head command.
Linux tail command syntax
tail [OPTION]… [FILE]…
Tail is a command which prints the last few number of lines (10 lines by default) of a certain file, then terminates.
Example 1: By default ???tail??? prints the last 10 lines of a file, then exits.
# tail /var/log/messages
Mar 20 12:42:22 hameda1d1c dhclient: DHCPREQUEST on eth0 to 255.255.255.255 port 67 (xid=0x280436dd)
Mar 20 12:42:24 hameda1d1c avahi-daemon: Registering new address record for fe80::4639:c4ff:fe53:4908 on eth0.*.
Mar 20 12:42:28 hameda1d1c dhclient: DHCPREQUEST on eth0 to 255.255.255.255 port 67 (xid=0x280436dd)
Mar 20 12:42:28 hameda1d1c dhclient: DHCPACK from 10.76.198.1 (xid=0x280436dd)
Mar 20 12:42:30 hameda1d1c avahi-daemon: Joining mDNS multicast group on interface eth0.IPv4 with address 10.76.199.87.
Mar 20 12:42:30 hameda1d1c avahi-daemon: New relevant interface eth0.IPv4 for mDNS.
Mar 20 12:42:30 hameda1d1c avahi-daemon: Registering new address record for 10.76.199.87 on eth0.IPv4.
Mar 20 12:42:30 hameda1d1c NET: /sbin/dhclient-script : updated /etc/resolv.conf
Mar 20 12:42:30 hameda1d1c dhclient: bound to 10.76.199.87 — renewal in 74685 seconds.
Mar 20 12:45:39 hameda1d1c kernel: usb 3-7: USB disconnect, device number 2
as you can see, this prints the last 10 lines of /var/log/messages.
Example 2: Now what about you are interested in just the last 3 lines of a file, or maybe interested in the last 15 lines of a file. this is when the -n option comes handy, to choose specific number of lines instead of the default 10.
tail -n /path/to/file
# tail -n 4 /etc/group
Example 3: We can even open multiple files using tail command with out need to execute multiple tail commands to view multiple files. Suppose if you want to see first two lines of a
[email protected]:~/code/sh$ tail -n 2 99abc.txt startup_script.sh wifiactivate.sh
== 99abc.txt startup_script.sh wifiactivate.sh