grep command

 grep -v "^#|^$" filename 

^# :- line start with comment #

^$ :- empty lines 

[a-zA-Z0-9_] :- alpha numeric with _ 

grep -o "^.\{1,10\}" filename  :- find first 10 character word at the beginning of line.

grep -o ".\{1,10\}$" filename :- find last 10 character word at the end of line.

grep -o "^." filename  :- find one character for beginning of each line.

grep -o ".$" filename  :- find one character for end of the each line.

grep -e "^$" filename :- find the empty lines in the file.

grep -e "$" filename :- end of the line.

grep -e "^[a-zA-Z\]\{0,255\}\+\@\+[a-zA-Z\]\{0,255\}\+\:\+\~\+\\$" fun.txt : kayyum@AbdulKayyum:~$

grep -v "^[a-zA-Z\]\{0,255\}\+\@\+[a-zA-Z\]\{0,255\}\+\:\+\~\+\\$" fun.txt  : kayyum@AbdulKayyum:~$

kayyum@AbdulKayyum:~$ cat new.txt | grep -e "grep\|#" | grep -o "grep.*\|#.*"

# grep :- remove empty lines

grep -v "^$" sample.txt

# grep :- remove commented lines.

grep -v "^#" sample.txt

# grep :- to find oracle datafiles

grep -o "[a-zA-Z0-9_\]\{0,255\}\.dbf" sample.txt

# grep :- find first 10 characters each line

grep -o "^.\{1,10\}" sample.txt

# grep :- find last 10 characters each line

grep -o ".\{1,10\}$" sample.txt

# grep :- remove commented and empty lines

grep -v "^#\|^$" sample.txt

# grep :- to find ' " ' double quotes in the file

grep -e "\"" file.txt

# grep :- to find '{ ' and '}' curly braces

grep -e "\{" file.txt

grep -e "\}" file.txt

# combine

grep -e "\{\|\}" file.txt

grep -e "\"\.\"" file.txt

grep -e "[a-zA-Z\]\{0,255\}" file.txt