SED COMMAND ON LINUX

to view file content with line number:-

cat -n file.txt 

-- to delete last line in the file :-

sed -i '$d' filename 

-- to delete first line in the file :-

sed -i '1d' filename 

-- to append something 

[root@localhost ~]# sed -i '$a\

> export ORACLE_HOME=/u02/ogg19c\

> export PATH=$ORACLE_HOME/bin:$PATH\

> export LD_LIBRARY_PATH=$ORACLE_HOME/lib

> ' bash_profile

[root@localhost ~]# cat bash_profile

india

is my country

export ORACLE_HOME=/u02/ogg19c

export PATH=$ORACLE_HOME/bin:$PATH

export LD_LIBRARY_PATH=$ORACLE_HOME/lib

in above :- $ taken for last line of the file so append in the last.

-- to delete lines from file using sed command 

[root@localhost ~]# cat -n bash_profile

     1  india

     2  is my country

     3  export ORACLE_HOME=/u02/ogg19c

     4  export PATH=$ORACLE_HOME/bin:$PATH

     5  export LD_LIBRARY_PATH=$ORACLE_HOME/lib

[root@localhost ~]# # delete line number ---> 3 and 5 using below 

[root@localhost ~]# sed -i '3,5d' bash_profile

[root@localhost ~]#

[root@localhost ~]# cat -n bash_profile

     1  india

     2  is my country