Summary of common grep commands

1. grep is the simplest method to use. match a word: grep word filename

2. Match: grep word filename1 filenam2 filename3 from multiple files

3. You can use a regular expression to match: grep-e pattern F1 F2 F3...

4. You can use-O to print only matching characters, as shown below:

[email protected]:command$ echo this is a line. | grep -E -o "[a-z]*\."line.

5. Print the rows other than matching rows, and use-V

[email protected]:command$ echo -e "1\n2\n3\n4" | grep -v -E "[1-2]"34

6. count the number of rows that match the string. Use-C

[email protected]:command$ echo -e "1111\n2222" | grep -E "[1-2]" -c2

7. If we count the number of times the string mode matches, we can combine-O and-C, as shown below:

[email protected]:command$ echo -e "1111\n2222" | grep -o -E "[1-2]"  | wc -l8

8. to display the row number, open-N, as shown below:

[email protected]:command$ echo -e "1111\n2222\n33333\n44444" | grep -n -E "3"3:33333

9. The-B option can print the offset (starting from 0) of the starting position of the row where the matched string is located. It is usually used with-o, as follows:

[email protected]:command$ echo "0123456789" | grep -b -o 44:4

10. When the string matches multiple files, the-L option prints only the file name.

11.-L is opposite to-L. Only file names that do not match are printed.

[email protected]:command$ cat test1.txtlinuxisfun[email protected]:command$ cat test2.txta verypopular os,linux[email protected]:command$ cat test3.txtwhatthefxxk[email protected]:command$ grep -l linux test1.txt test2.txt test3.txttest1.txttest2.txt[email protected]:command$ grep -L linux test1.txt test2.txt test3.txttest3.txt

12. Enable recursive search

[email protected]:command$ grep -n -R linux . ./test2.txt:5:linux./test1.txt:1:linux

13. Ignore case sensitivity:-I

[email protected]:command$ echo "HELLO WORLD" | grep -i "hello"HELLO WORLD

14. Match multiple string Modes

[email protected]:command$ echo "This is a line." | grep -e "This" -e "is" -e "line" -oThisisline

15. A matching style is provided with a separate file, and each matching style is taken as a line, as shown in the following example:

[email protected]:command$ cat pattern.txt1$23[email protected]:command$ cat num.txt 12345678910[email protected]:command$ grep -f pattern.txt num.txt 123

16. print the context information of the matching row, use-a n to print the information of the matching row and the last n rows, use-B n to print the information of the matching row and the first n rows, and use-C n, print the information of matching rows and the N rows before and after them. If Multiple matching rows exist, -- isolation is used. Example:

[email protected]:command$ seq 1 10 | grep 5 -A 35678[email protected]:command$ seq 1 10 | grep 5 -B 32345[email protected]:command$ seq 1 10 | grep 5 -C 32345678[email protected]:command$ echo -e "a\nb\nc\nd\na\nb\nc\nd\n" | grep a -A 2abc--abc

17. Use-Q to enter silent mode. In this mode, the grep command runs only to execute a conditional test, which is usually used in scripts. Perform the next step by checking its return value. Example:

[email protected]:command$ cat tmp.txthelloworld[email protected]:command$ cat tmp.csh#!/bin/bashif [ $# -ne 2 ]; thenecho "Usage: $0 match_pattern file_name"exitfimatch=$1file=$2grep -q $match $fileif [ $? -ne 0 ]; thenecho "$match not exist in $file"elseecho "$match exist in $file"fi[email protected]:command$ ./tmp.csh hello tmp.txthello exist in tmp.txt

18. When the-Z option is used to output a matching file name, it will end with/0 with xargs-0. For example, deleting a file that matches a certain pattern is as follows:

[email protected]:command$ ls -llrttotal 28-rw-rw-r-- 1 lichao lichao  13 Nov  1 20:38 test1.txt-rw-rw-r-- 1 lichao lichao  27 Nov  1 20:39 test2.txt-rw-rw-r-- 1 lichao lichao  14 Nov  1 20:39 test3.txt-rw-rw-r-- 1 lichao lichao  21 Nov  1 20:45 num.txt-rw-rw-r-- 1 lichao lichao   7 Nov  1 20:45 pattern.txt-rw-rw-r-- 1 lichao lichao  12 Nov  1 21:25 tmp.txt-rwxr-xr-x 1 lichao lichao 217 Nov  1 21:27 tmp.csh[email protected]ntu:command$ cat test1.txtlinuxisfun[email protected]:command$ cat test2.txta verypopular os,linux[email protected]:command$ grep "linux" * -lZ | xargs -0 rm[email protected]:command$ lsnum.txt  pattern.txt  test3.txt  tmp.csh  tmp.txt

Delete test1.txtand test2.txt in the linuxlinuxstring by using the command above.

19. exclude/include files or directories: 1) -- include *{. C ,. CPP} Only searches in the directory. C and. CPP file; 2) -- exclude "readme" exclude all README files 3) -- include-Dir search only in some Directories 4) -- exclude-Dir exclude some directories 5) -- exclude-from file: read the list of files to be excluded from the file.

[email protected]:test$ lsdir1  dir2  exclude.config  test1.txt  test2.doc  test3.word[email protected]:test$ cat test1.txt linux is fun[email protected]:test$ cat test2.doc wonderful os,linux[email protected]:test$ cat test3.word wonderful os,linux[email protected]:test$ ls dir1/test1.txt  test2.doc  test3.word[email protected]:test$ ls dir2/test1.txt  test2.doc  test3.word[email protected]:test$ cat exclude.config *.txt[email protected]:test$ grep "linux" -R -n . ./test2.doc:3:linux./test3.word:3:linux./test1.txt:1:linux ./dir2/test2.doc:3:linux./dir2/test3.word:3:linux./dir2/test1.txt:1:linux ./dir1/test2.doc:3:linux./dir1/test3.word:3:linux./dir1/test1.txt:1:linux [email protected]:test$ grep "linux" -R -n . --include *.txt --include *.doc./test2.doc:3:linux./test1.txt:1:linux ./dir2/test2.doc:3:linux./dir2/test1.txt:1:linux ./dir1/test2.doc:3:linux./dir1/test1.txt:1:linux [email protected]:test$ grep "linux" -R -n . --exclude *.txt --eclude *.docgrep: unrecognized option '--eclude'Usage: grep [OPTION]... PATTERN [FILE]...Try 'grep --help' for more information.[email protected]:test$ grep "linux" -R -n . --exclude *.txt --exclude *.doc./test3.word:3:linux./dir2/test3.word:3:linux./dir1/test3.word:3:linux[email protected]:test$ grep "linux" -R -n . --exclude-dir dir1./test2.doc:3:linux./test3.word:3:linux./test1.txt:1:linux ./dir2/test2.doc:3:linux./dir2/test3.word:3:linux./dir2/test1.txt:1:linux [email protected]:test$ grep "linux" -R -n . --exclude-dir dir1 --exclude-dir dir2./test2.doc:3:linux./test3.word:3:linux./test1.txt:1:linux [email protected]:test$ grep "linux" -R -n . --exclude-from exclude.config ./test2.doc:3:linux./test3.word:3:linux./dir2/test2.doc:3:linux./dir2/test3.word:3:linux./dir1/test2.doc:3:linux./dir1/test3.word:3:linux

It is a common grep option.

Note: Please indicate the source for reprinting.

Summary of common grep commands