In the Linux system, cat command is a command to output text, usually used to view the contents of a document. It has the following three functions:
1, a one-time display the whole file
Such as: see / etc / initab file, you can use the command: cat / etc / inittab
2, create a file from the keyboard
Such as: command: cat> five.txt, and then enter some text messages, you can exit directly Ctrl + C.
3, several files into one file
如：命令：catfive.txt six.txt > fivesix.txt
Command cat command format: cat [option] [file]
Command parameters:
-A, --show-all equivalent -vET
-b, --number-nonblank number nonempty output lines
-e equivalent to -vE
-E, --show-ends display $ at the end of each line
-n, --number numbers for all lines output by 1 start number for the number of lines for all outputs
-s, --squeeze-blank with more than two successive blank lines, one line on the blank line substitution
-t equivalent and -vT
-T, --show-tabs the tab character is displayed as ^ I
-u (ignored)
Description: tac is cat written anti-over, so his function like cat contrast, the cat is continuously displayed by the last line of the first line on the screen, and tac is the last line to the first line on the screen in reverse show.