Linux / Unix: Add Line Numbers To Files

Posted on in Categories , , , last updated March 19, 2013

I know how to display line numbers using vim text editor. How do display line numbers in the left side for any text file under Unix or Linux operating systems?

You can use any one of the following commands to display line numbers:

[a] cat command

[b] nl command – Display each FILE to standard output (screen), with line numbers added.

[c] Gnu less command – Less is a program similar to more , but which allows backward movement in the file as well as forward movement

[d] awk command

[e] perl or python

Examples

The cat command syntax is:

cat -n file
cat -n /etc/hosts

The nl command syntax is:

nl file
nl /etc/hosts

Sample outputs:

     1	127.0.0.1 localhost
     2	#127.0.1.1 wks01.WAG160N wks01.nixcraft.net.in
     3	192.168.1.5	wks01
     4	# The following lines are desirable for IPv6 capable hosts
     5	::1 ip6-localhost ip6-loopback
     6	fe00::0 ip6-localnet
     7	ff00::0 ip6-mcastprefix
     8	ff02::1 ip6-allnodes
     9	ff02::2 ip6-allrouters
    10	10.10.29.72 v.b1 homerouter
    11	10.10.29.70 v.b2
    12	10.10.29.68 v.txvip1

The less command syntax is:

less -N file
less -N /etc/hosts

The awk command syntax is:

awk '{ print FNR " " $0 }' file
awk '{ print FNR " " $0 }' /etc/hosts
awk '{ print FNR "\t" $0 }' /etc/hosts

The perl syntax is:

perl -pe '$_ = "$. $_"' file
perl -pe '$_ = "$. $_"' /etc/hosts

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

2 comment

  1. Hello Vivek!

    The below FNR didnt work in my environment. I am using Solaris 10.
    awk '{ print FNR " " $0 }' file

    But NR worked !
    awk '{print NR," " $0}' file

    Can you confirm if FNR is working?

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