Grep Command In Unix/Linux: Basic Command
Grep – associate degree Introduction:
Greep could be a command-line utility for looking out plain-text datasets for lines matching an everyday expression. Grep was originally developed for the operating system software system by Ken Thompson, however, is out there these days for all Unix-like systems. Its name comes from the disfunction command g/re/p (globally search an everyday expression and print), that has an equivalent effect: doing a worldwide search with the regular expression and printing all matching lines.
Find Syntax:
grep “literal_string” file name.
14 Examples:
1: Search for the string in a single file.
Syntax: grep “literal_string” file name
Example: $ grep “this” demo_file
2: Searching for the string in many files.
Syntax: grep “string” FILE_PATTERN.
Example: $ grep “this” demo_*
3: Case insensitive search.
Syntax: grep-i “string” FILE.
Example: $ grep -i “the” demo_file.
4: Searching for the string in many files.
Syntax: grep “lines.*empty” demo_file
- ? The preceding item is optional and matched at the most once.
- * Preceding item will be matched zero or more times.
- + The preceding item will be matched one or more times.
- {n} The preceding item is matched exactly n times.
- {n,} The preceding item is matched n or more times.
- {,m} The preceding item is matched at most m times.
- {n,m} The preceding item is matched at least n times, but not more than m times.
5: Full words search.
Example: grep -iw “is” demo_file
6: Display N lines after the match.
Syntax: grep -A <N> “string” FILENAME.
Example: grep -A 3 -i “example” demo_text
7: Display N lines before the match.
Syntax: grep -B <N> “string” FILENAME.
Example: grep -B 2 “single WORD” demo_text.
8: Display n line around the match.
Syntax: grep -c <N> “string” FILENAME.
Example: grep -C 2 “Example” demo_text.
9: Recursively Searching.
Example: grep -r “ramesh” *
10: Invert searching.
Example: grep -v “go” demo_text.
11: Counting the number of matches.
Syntax: grep -c “pattern” filename.
Example: grep -c “go” demo_text.
12: Display only the file names which match the given pattern.
Example: grep -I this demo_*
13: Show the position of match in the line.
Syntax: grep -o -b “pattern” file.
Example: grep -o -b “3” temp-file.txt.
o = match only string
b = show position
14: Show line number while displaying the output.
Syntax: grep -n “go” demo_txt.
These are the 14 best examples for grep command in Unix.
Leave a Reply