Linux diff command

Comprehensive List of Linux Commands

The Linux diff command is used to compare file differences.

diff compares the differences between text files line by line. If a directory is specified, diff will compare files with the same name in the directory but will not compare files in subdirectories.

Syntax

diff 　[-abBcdefHilnNpPqrstTuvwy][-<line number>][-C 　<line number>][-D 　<macro name>][-I 　<character or string>][-S 　<file>][-W 　<width>][-x 　<file or directory>][-X 　<file>][--help][--left-column][--suppress-common-line][file or directory1][file or directory2]

parameter:

• -<line number> 　Specify how many lines of text to display. This parameter must be used with-or-use the u parameter together.

• -or--text 　diff preset only compares text files line by line.

• -b or--ignore-space-change 　Does not check for differences in space characters.

• -B or--ignore-blank-lines 　Does not check for blank lines.

• -c 　Displays the full content and marks the differences.

• -C<line number> or--context<line number> 　With the execution"-c-<line number>"Command is the same.

• -d or--minimal 　Uses different algorithms to compare in smaller units.

• -D<macro name> or ifdef<macro name> 　The output format of this parameter can be used for preprocessor macros.

• -e or--ed 　The output format of this parameter can be used for the ed script file.

• -f or-forward-ed 　The output format is similar to the ed script file, but the differences are displayed in the order of the original file.

• -H or--speed-large-files 　Can speed up the process when comparing large files.

• -l<character or string> or--ignore-matching-lines<character or string> 　If two files differ in some lines, and these lines both contain the character or string specified in the option, then do not display the differences between these two files.

• -i or--ignore-case 　Does not check for differences in case.

• -l or--paginate 　Hands the result over to the pr program for pagination.

• -n or--rcs 　Displays the comparison result in the RCS format.

• -N or--new-file 　When comparing directories, if file A only appears in a certain directory, the default is to display:

• Only in directory: If file A is used in-N parameter, then diff will compare file A with an empty file.

• -p 　If the compared file is a C program code file, displays the function name where the difference is located.

• -P or--unidirectional-new-file 　With-N similar, but only compares the file that the second directory contains and the first directory does not to an empty file.

• -q or--brief 　Displays only whether there are differences without showing detailed information.

• -r or--recursive 　Compares files in subdirectories.

• -s or--report-identical-files 　Displays information even if no differences are found.

• -S<file> or--starting-file<file> 　When comparing directories, starts the comparison from the specified file.

• -t or--expand-tabs 　Expands tab characters when outputting.

• -T or--initial-tab 　Adds a tab character at the beginning of each line for alignment.

• -u,-U<column number> or--unified=<column number> 　Displays the differences in file content in a merged manner.

• -v or--version 　Displays version information.

• -w or--ignore-all-space 　Ignore all space characters.

• -W<width> or--width<width> 　When using-When using y parameter, specify the column width.

• -x<filename or directory> or--exclude<filename or directory> 　Do not compare the specified files or directories in the options.

• -X<file> or--exclude-from<file> 　You can save the file or directory type as a text file, and then specify this text file in=<file>.

• -y or--side-by-side 　Display the differences between files in parallel.

• --help 　Display help.

• --left-column 　When using-When using y parameter, if the content of a line in two files is the same, then only the content in the left column is displayed.

• --suppress-common-lines 　When using-When using y parameter, only the differences are displayed.

Example1:Compare two files

[root@localhost test3# diff log2014.log  log2013.log　
3c3
<　2014-03
---
>　2013-03
8c8
<　2013-07
---
>　2013-08
11,12d10
<　2013-11
<　2013-12

The above "3c3" and "8c8" indicates that the log2014.log and log20143log file is in3Line and the8Line content is different;11,12d10" indicates that the first file has more than the second file11And12Line.

Example2Side-by-side format output

[root@localhost test3# diff log2014.log  log2013.log　　-y　-W　50
2013-01　　　　　　　　　　　　　　　　　2013-01
2013-02　　　　　　　　　　　　　　　　　2013-02
2014-03　　　　　　　　　　　　　　　|　2013-03
2013-04　　　　　　　　　　　　　　　　　2013-04
2013-05　　　　　　　　　　　　　　　　　2013-05
2013-06　　　　　　　　　　　　　　　　　2013-06
2013-07　　　　　　　　　　　　　　　　　2013-07
2013-07　　　　　　　　　　　　　　　|　2013-08
2013-09　　　　　　　　　　　　　　　　　2013-09
2013-10　　　　　　　　　　　　　　　　　2013-10
2013-11　　　　　　　　　　　　　　　<
2013-12　　　　　　　　　　　　　　　<
[root@localhost test3# diff log2013.log  log2014.log　　-y　-W　50
2013-01　　　　　　　　　　　　　　　　　2013-01
2013-02　　　　　　　　　　　　　　　　　2013-02
2013-03　　　　　　　　　　　　　　　|　2014-03
2013-04　　　　　　　　　　　　　　　　　2013-04
2013-05　　　　　　　　　　　　　　　　　2013-05
2013-06　　　　　　　　　　　　　　　　　2013-06
2013-07　　　　　　　　　　　　　　　　　2013-07
2013-08　　　　　　　　　　　　　　　|　2013-07
2013-09　　　　　　　　　　　　　　　　　2013-09
2013-10　　　　　　　　　　　　　　　　　2013-10
　　　　　　　　　　　　　　　　　　　　　　>　2013-11
　　　　　　　　　　　　　　　　　　　　　　>　2013-12

Note:

• "|" indicates the content before and after2There are different contents in the file

• "<" indicates that the file after it is smaller than the file before it1Line Content

• ">" indicates that the file after it is larger than the file before it1Line Content

Comprehensive List of Linux Commands