grep shell of operations

GREP

grep (Global search Regular Expression and Print out the line) is a powerful text search tool, it can use a regular expression search text, and print out the matching rows.

grep example

1. grep 'word' filename: Search for files contain word lines;
2. grep -i 'bar' file1: Case-insensitive search bar in the file;
3. grep -R foo: Search for the word foo in the current folder and its subfolders;
4. grep -c 'nixcraft' frontpage.md: Search for and displays the number of 'nixcraftq' frontpage.md appear in the file;

Linux and unix syntax of

grep 'word' filename
grep 'word' file1 file2 file3
grep 'string1 string2'  filename
cat otherfile | grep 'something'
command | grep 'something'
command option1 | grep 'data'
grep --color 'data' fileName

Use grep search files in linux

In the / etc / passwd file search boo:

grep boo /etc/passwd

Case-insensitive search boo, Boo BOO and so on:

grep -i "boo" /etc/passwd

Finally grep command may follow the cat:

cat /etc/passwd | grep -i "boo"

Iteration

-R or -r parameter can be iterated to find in folders and sub-folders

grep -r "192.168.1.5" /etc/

Returns

/etc/ppp/options:# ms-wins 192.168.1.50
/etc/ppp/options:# ms-wins 192.168.1.51

-h parameter can omit the filename, -n parameter display line numbers:

Only a single word search

When using grep search boo, returned may have fooboo, boo123 and so on. -w parameter can only search a boo word:

grep -w "boo" file

Search two different words

Use egrep name:

egrep -w 'word1|word2' file

The number of rows to be displayed matching file

The -c parameter, grep can report the number of lines in each file matches

grep -c 'word' /path/to/file

No match display

The -v argument can not match the print line:

grep -v 'bar' /path/to/file

linux pipes and grep

grep parameters may be used in pipes, use the |command.
For example cpu print mode

cat /proc/cpuinfo | grep -i 'Model'

It may be combined apt searchto find the installation package

Listed successfully matched filenames

Use the -l command to list the file name contains the main () is:

grep -l 'main' *.c

to sum up

parameter	description
-i	Ignore case
-n	Only whole words
-v	Select not match mode
-n	Print line numbers
-h	Does not display the file name
-r	Iteration
-R	Iteration
-l	Print only successful match the file name
-c	The number of lines to print documents only successfully matched
--color	Use color display successful match