Linux — cat 查看文件内容
CAT(1) User Commands CAT(1)
NAME 名称
cat – concatenate files and print on the standard output
连接文件，将文件内容显示在标准输出上
SYNOPSIS 语法
cat [OPTION]… [FILE]…
DESCRIPTION 说明
Concatenate FILE(s), or standard input, to standard output.
连接文件，或标准输入，显示在标准输出上。
-A, –show-all
equivalent to -vET
等同于-vET。
-b, –number-nonblank
number nonempty output lines, overrides -n
对非空行进行编号，同-n一起使用时，-n无效。
-e
equivalent to -vE
等同于-vE。
-E, –show-ends
display $ at end of each line
在每行结尾显示$符号。
-n, –number
number all output lines
对每行进行编号，包括空行。
-s, –squeeze-blank
suppress repeated empty output lines
当遇到两行及以上空行时，仅显示一行。
-t
equivalent to -vT
等同于-vT。
-T, –show-tabs
display TAB characters as ^I
将TAB字符用^I显示。
-u (ignored)
忽略。
-v, –show-nonprinting
use ^ and M- notation, except for LFD and TAB
除LFD和TAB之外，使用^和M-字符显示非ASCII字符。
–help
display this help and exit
显示帮助信息并退出。
–version
output version information and exit
显示版本信息并退出。
With no FILE, or when FILE is -, read standard input.
当没有指定文件或文件占位符用’-‘代替，则从标准输入读取。
EXAMPLES 举例
cat f – g
Output f’s contents, then standard input, then g’s contents.
输出f的内容，然后是从标准输入设备读取的内容，最后是g的内容。
cat Copy standard input to standard output.
输出从标准输入设备读取的内容到标准输出。
GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Report cat translation bugs to <http://translationproject.org/team/>
AUTHOR 作者
Written by Torbjorn Granlund and Richard M. Stallman.
COPYRIGHT 版权
Copyright (C) 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
tac(1)
The full documentation for cat is maintained as a Texinfo manual. If the info and cat programs are properly installed at your site, the command
info coreutils ‘cat invocation’
should give you access to the complete manual.
cat的完整文档是以Texinfo手册形式维护的。如果info和cat程序都已经安装，那么执行命令：
info coreutils ‘cat invocation’
应该会让你访问到整篇手册。
GNU coreutils 8.22 June 2014 CAT(1)
案例分析：
一、原始文件及内容
[root@user test]# ls
test.txt
[root@user test]# cat test.txt
abcdefghijklmnopqrstuvwxyz
cdefghijklm nopqrstuvwxyzab
defghijklmnopqrstuvwxyzabc
efghijklmnopqrstuvwxyzabcd
ijklmnopqrstuvwxyzabcdefgh
9ijklmnopqrstuvwxyzabcdefgh
瞄瞄
呀
sadfsdf9 00-=-+!@#$%^&
■▲△→↑↓￣︿＠
[root@user test]#
二、查看test.txt内容及行号
[root@user test]# cat -n test.txt
1 abcdefghijklmnopqrstuvwxyz
2 cdefghijklm nopqrstuvwxyzab
3 defghijklmnopqrstuvwxyzabc
4
5 efghijklmnopqrstuvwxyzabcd
6
7
8 ijklmnopqrstuvwxyzabcdefgh
9 9ijklmnopqrstuvwxyzabcdefgh
10
11 瞄瞄
12 呀
13 sadfsdf9 00-=-+!@#$%^&
14 ■▲△→↑↓￣︿＠
[root@user test]#
三、查看test.txt内容及行号，空行不编号
[root@user test]# cat -b test.txt
1 abcdefghijklmnopqrstuvwxyz
2 cdefghijklm nopqrstuvwxyzab
3 defghijklmnopqrstuvwxyzabc
4 efghijklmnopqrstuvwxyzabcd
5 ijklmnopqrstuvwxyzabcdefgh
6 9ijklmnopqrstuvwxyzabcdefgh
7
8 瞄瞄
9 呀
10 sadfsdf9 00-=-+!@#$%^&
11 ■▲△→↑↓￣︿＠
[root@user test]#
四、查看test.txt内容及行号，多空行仅显示一行
[root@user test]# cat -sn test.txt
1 abcdefghijklmnopqrstuvwxyz
2 cdefghijklm nopqrstuvwxyzab
3 defghijklmnopqrstuvwxyzabc
4
5 efghijklmnopqrstuvwxyzabcd
6
7 ijklmnopqrstuvwxyzabcdefgh
8 9ijklmnopqrstuvwxyzabcdefgh
9
10 瞄瞄
11 呀
12 sadfsdf9 00-=-+!@#$%^&
13 ■▲△→↑↓￣︿＠
[root@user test]#
五、查看test.txt内容及行号，多空行仅显示一行，TAB和每行结尾加标识
[root@user test]# cat -snTE test.txt
1 abcdefghijklmnopqrstuvwxyz$
2 cdefghijklm^Inopqrstuvwxyzab$
3 defghijklmnopqrstuvwxyzabc$
4 $
5 efghijklmnopqrstuvwxyzabcd$
6 $
7 ijklmnopqrstuvwxyzabcdefgh$
8 9ijklmnopqrstuvwxyzabcdefgh$
9 ^I$
10 瞄瞄$
11 呀$
12 sadfsdf9^I00-=-+!@#$%^&$
13 ■▲△→↑↓￣︿＠$
[root@user test]#
六、-v显示
[root@user test]# cat -v test.txt
abcdefghijklmnopqrstuvwxyz
cdefghijklm nopqrstuvwxyzab
defghijklmnopqrstuvwxyzabc
efghijklmnopqrstuvwxyzabcd
ijklmnopqrstuvwxyzabcdefgh
9ijklmnopqrstuvwxyzabcdefgh
M-gM-^^M-^DM-gM-^^M-^D
M-eM-^QM-^@
sadfsdf9 00-=-+!@#$%^&
M-bM-^VM- M-bM-^VM-2M-bM-^VM-3M-bM-^FM-^RM-bM-^FM-^QM-bM-^FM-^SM-oM-?M-#M-oM-8M-?M-oM-<M-
[root@user test]#