How to use the Linux nl command

 : : : : : : : : : : : : : : : CC is the two delimiters used to separate logical page numbers. The missing second character implies ":". If you specify "\", 
Please enter "\\". The available styles are: 

 a Number all lines t Number non-blank lines n Do not number lines pBRE Number only lines that match the regular expression BRE FORMAT is one of the following: 

 ln Left-aligned, no spaces are filled with 0rn Right-aligned, no spaces are filled with 0rz Right-aligned, spaces are filled with 0

[root@oracledb study]# nl test1.log 
   1 2011
   2 2012
   3 2013

[root@oracledb study]# nl -nln test1.log 
1 2011
2 2012
3 2013
[root@oracledb study]# nl -nrn test1.log 
   1 2011
   2 2012
   3 2013
[root@oracledb study]# nl -nrz test1.log 
000001 2011
000002 2012
000003 2013

[root@oracledb study]# nl -nrz -w 4 test1.log 
0001 2011
0002 2012
0003 2013

[root@oracledb study]# nl
line1
   1 line1
line2 
   2 line2
line3
   3 line3
[root@oracledb study]#

[root@oracledb study]# nl <<EOF
> line1
> line2
> line3
> EOF
   1 line1
   2 line2
   3 line3