SED
sed 's/day/night/g' old >new
sed 's/[a-z]*/(&)/' old >new
replace \n
sed -e :a -e '$!N;s/\n/ /;ta' old >new
replace \n
sed -e :a -e '$b;N;s/\n/ /;ba' old >new
selectively select line to replace
sed '/^SPECIAL_TEXT/s/to_be_replaced/replace_by/g' old >new
show only changed ones
sed -n 's/to_be_replaced/replace_by/p' old >new
show only changed ones conditionally
sed -n 's/\b[Nn]andan\b/NANDAN/p' old >new
echo Today is 15 Feb 2010 | sed 's/[0-9]\{1,2\} \+[A-Za-z][a-z]\+/*&*/' o\p: Today is *15 Feb* 2010
delete nth line
sed 'nd' 2.txt > 2.int
delete 1st line
sed -i -e 1d 2.txt
delete last line
sed '$d' f.txt
delete all empty lines
sed '/^$/d' f.txt
sed '/./!d' f.txt
delete between lines m and n
sed 'm,nd' f.txt
delete all lines having word name
sed '/name/d' f.txt
replace
`echo $i| sed "s/.mpeg.txt$//"`.txt
change columns into line
sed -e :a -e '$!N;s/\n/ /;ta' file1 > file 2