Linux -- cat to view file contents
CAT(1) User Commands CAT(1)
NAME
cat - concatenate files and print on the standard output
concatenates files and displays the contents of the file on standard output
SYNOPSIS syntax
cat [OPTION]... [FILE]...
DESCRIPTION
Concatenate FILE(s), or standard input, to standard output.
The connection file, or standard input, is displayed on standard output.
-A, --show-all
equivalent to -vET
Equivalent to -vET.
-b, --number-nonblank
number nonempty output lines, overrides -n
Number non-blank lines. When used with -n, -n has no effect.
-e equivalent to -vE
Equivalent to -vE.
-E, --show-ends
display $ at end of each line
Display a $ sign at the end of each line.
-n, --number
number all output lines
Number each line, including blank lines.
-s, --squeeze-blank
suppress repeated empty output lines
When two or more blank lines are encountered, only one line is displayed.
-t equivalent to -vT
Equivalent to -vT.
-T, --show-tabs
display TAB characters as ^I
Display the TAB character with ^I.
-u (ignored)
neglect.
-v, --show-nonprinting
use ^ and M- notation, except for LFD and TAB
In addition to LFD and TAB, use the ^ and M- characters to display non-ASCII characters.
--help display this help and exit
Display help information and exit.
--version
output version information and exit
Display version information and exit.
With no FILE, or when FILE is -, read standard input.
When no file is specified or the file placeholder is replaced with '-', the standard input is read.
EXAMPLES
cat f - g
Output f's contents, then standard input, then g's contents.
Output the contents of f, then the contents read from the standard input device, and finally the contents of g.
cat Copy standard input to standard output.
Output what is read from the standard input device to standard output.
GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Report cat translation bugs to <http://translationproject.org/team/>
AUTHOR Author
Written by Torbjorn Granlund and Richard M. Stallman.
COPYRIGHT Copyright
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.
The complete documentation for cat is maintained as a Texinfo manual. If both the info and cat programs are installed, execute the command:
info coreutils 'cat invocation'
should give you access to the entire manual.
GNU coreutils 8.22 June 2014 CAT(1)
case analysis:
1. Original documents and content
[root@user test]# ls test.txt [root@user test]# cat test.txt abcdefghijklmnopqrstuvwxyz cdefghijklm nopqrstuvwxyzab defghijklmnopqrstuvwxyzabc efghijklmnopqrstuvwxyzabcd ijklmnopqrstuvwxyzabcdefgh 9ijklmnopqrstuvwxyzabcdefgh take aim Ah sadfsdf9 00-=-+!@#$%^& ■▲△→↑↓￣︿＠ [root@user test]#
2. View the content and line number of test.txt
[root@user test]# cat -n test.txt
1 abcdefghijklmnopqrstuvwxyz
2 cdefghijklm nopqrstuvwxyzab
3 defghijklmnopqrstuvwxyzabc
4
5 efghijklmnopqrstuvwxyzabcd
6
7
8 ijklmnopqrstuvwxyzabcdefgh
9 9ijklmnopqrstuvwxyzabcdefgh
10
11 Aim
12
13 sadfsdf9 00-=-+!@#$%^&
14 ■▲△→↑↓￣︿＠
[root@user test]#
3. Check the content and line number of test.txt, blank lines are not numbered
[root@user test]# cat -b test.txt
1 abcdefghijklmnopqrstuvwxyz
2 cdefghijklm nopqrstuvwxyzab
3 defghijklmnopqrstuvwxyzabc
4 efghijklmnopqrstuvwxyzabcd
5 ijklmnopqrstuvwxyzabcdefgh
6 9ijklmnopqrstuvwxyzabcdefgh
7
8 Aim
9
10 sadfsdf9 00-=-+!@#$%^&
11 ■▲△→↑↓￣︿＠
[root@user test]#
4. Check the content and line number of test.txt, only one line is displayed for multiple empty lines
[root@user test]# cat -sn test.txt
1 abcdefghijklmnopqrstuvwxyz
2 cdefghijklm nopqrstuvwxyzab
3 defghijklmnopqrstuvwxyzabc
4
5 efghijklmnopqrstuvwxyzabcd
6
7 ijklmnopqrstuvwxyzabcdefgh
8 9ijklmnopqrstuvwxyzabcdefgh
9
10 Aim
11 Yeah
12 sadfsdf9 00-=-+!@#$%^&
13 ■▲△→↑↓￣︿＠
[root@user test]#
5. Check the content and line number of test.txt, only one line is displayed for multi-blank lines, and TAB and the end of each line are marked
[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 Aim $
11 ya$
12 sadfsdf9^I00-=-+!@#$%^&$
13 ■▲△→↑↓￣︿＠$
[root@user test]#
Six, -v display
[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]#