grep, egrep, fgrep - prints the lines with the search pattern
Syntax:
grep [options] "search pattern" <filename>
Examples:
1.
Searches for the pattern foo in the directory abc.
2.
| grep | Searches the pattern in a file for the lines matching the specified pattern |
| egrep | Advanced grepping where more than one pattern matching lines can be searched from a file using regular expressions |
| fgrep | Faster version of grepping, dosn't support regular expressions |
Syntax:
grep [options] "search pattern" <filename>
Examples:
1.
grep "foo" /home/abc/
Searches for the pattern foo in the directory abc.
2.
grep -R "foo" /home/abc/
Searches for the pattern foo in the directory and its sub directories recursively.
3.
grep -i "foo" /home/abc/
Searches for the patterns foo, Foo, fOo, foO, FOo, fOO, FoO, FOO in the directory abc. -i is used for case insensitive searches.
4.
grep -w "foo" /home/abc/
Searches for the word pattern foo in the directory abc. In this case the searched pattern is an exact word with name foo.
5.
grep -w "foo|bar" /home/abc/
Searches for the exact word patterns foo and bar. If any of the words gets matched, output will be displayed.
6.
grep -A2 "Alpha" abc.txt
It will display the next 2 lines after the search pattern.
7.
grep -B2 "Beta" abc.txt
It will display the previous 2 lines of the search pattern.
8.
grep -C2 "Gamma" abc.txt
It will display the previous 2 lines and next 2 lines of the search pattern.
9.
grep -v "Dog" abc.txt
It will search for all the lines that does not contain Dog in it.
10.
grep -c "Cat" abc.txt
It will give the number of lines that matched the search pattern.
11.
grep -n "Num" abc.txt
It will display the line number along with the line that matches the search pattern.
12.
grep --color "Color" abc.txt
It will display the matched line in color.