linux  grep  command with logical OR/AND operation

->OR  Operation
grep -nrl --color 'TOM \| DICK \|  HARRY' --include="*.txt"  *
grep -nrl --color 'sav2_base_test\|run_phase\|main_phase' --include="*.txt" * | wc -l                                    
This command lists TXT file names containing any of these keywords TOM , DICK or HARRY anywhere in file.

->AND Operation
grep -l  TOM * --include="*.txt" | xargs grep -l DICK | xargs grep -l HARRY 
grep -l  TOM * --include="*.txt" | xargs grep -l DICK | xargs grep -l HARRY | wc -l

This command lists TXT file names containing all of these keywords TOM , DICK or HARRY anywhere in file.


-->Find particular keyword and replace by other keyword in all files of given directory

find . -type f -exec sed -i 's/TOM/TOMMY/g' {} +

This command replaces all keywords TOM by TOMMY in all files of current directory.

For more info visit.

http://unix.stackexchange.com/questions/112023/how-can-i-replace-a-string-in-a-files 

Linux Grep Command

http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/

grep "literal_string" filename

grep "string" FILE_PATTERN

grep -i "string" FILE

grep "REGEX" filename

grep -iw "is" demo_file

grep -A <N> "string" FILENAME

grep -B <N> "string" FILENAME

grep -C 2 "Example" demo_text 

export GREP_OPTIONS='--color=auto' GREP_COLOR='100;8'
grep this demo_file

grep -r "DJ" * 

grep -v "go" demo_text

grep -v -e "pattern" -e "pattern"

grep -c "pattern" filename

grep -v -c this demo_file

grep -l this demo_*

grep -o "is.*line" demo_file

grep -o -b "pattern" file

grep -n "go" demo_text