grep – Global Regular Expression Parser
It is used to search data in one/more files.
Command 1: Search pattern in file
- grep hello file.txt
- grep sai file.txt file2.txt
Command 2: Search pattern in current folder with all txt extensions.
grep 1000 *.txt
Command 3: Search data in all files in current folder
grep 1000 *.*
Command 4: Search ignoring case[-i]
grep "Sai" file.txt (case sensitive by default)
grep -i "Sai" file.txt
Command 5: Display line number [-n]
grep -n "124" result.txt
Command 6: Get only filenames in which data exists[-l]
grep -l "100" *.*
Command 7: Search exact word [-w]
grep -w Sai file.txt
Command 8: Search lines of files which does not have that data(reverse of search)[-v]
grep -v "1000" file.txt
Command 9:
- Get one record before the search
grep -B 1 "Msd" file.txt
- Get one record after the search
grep -A 1 "Msd" file.txt
- Get one record before and after
search
grep -C 1 "Msd" file.txt
Command 10: Display no.of matches/Cound matches[-c](lower case)
grep -c "1000" file.txt
Command 11: Search multiple context in one command [-e]
grep -e "sai" -e "
kumar" file.txt
Command 12: egrep – Extended GREP
egrep 'Msd|Sai' file.txt