What does linux cat mean?

In Linux, the full name of cat is "concatenate", which means "connection". It can be used to connect files and print to the standard output device. The cat command can display the contents of a specified file or connect several files for display; the syntax is "cat [option] file name" or "cat file 1 file 2 > file 3".

#The operating environment of this tutorial: CentOS 6 system, Dell G3 computer.

In Linux, the full name of cat is "concatenate", which means "connection".

# The cat command is used to connect files and print to the standard output device. This command is often used to display the contents of a file, or to connect several files for display, or to read the content from the standard input and display it. It is often used in conjunction with the redirection symbol.

The cat command can be used to display the contents of a text file (similar to the type command under DOS), or to append the contents of several files to another file, that is, to connect and merge files. The basic format of the

cat command is as follows:

cat [选项] 文件名

or

cat 文件1 文件2 > 文件3

. Of the two formats, the former is used to display the contents of the file. Common options and their respective meanings are as shown in the table. 1; the latter is used to join merged files.

##- A is equivalent to the integration of the -vET option, used to list all hidden symbols; -E lists the carriage return character at the end of each line $;-nNumber all lines of output;-bSame as Unlike -n, this option means that only non-blank lines will be numbered. -TDisplay the Tab key^I; -VList Special characters; -sWhen encountering more than 2 consecutive blank lines, they will be replaced with 1 blank line.

Table 1 Cat command common options and their meanings

Options	Meaning

Note that when the cat command is used to view the contents of a file, it will be displayed at once regardless of the amount of file content. If the file is very large, the content at the beginning of the file will not be visible. However, Linux can use the

PgUp up arrow key combination to page up, but this page turning has its limits. If the file is long enough, you still cannot view the entire file content.

Therefore, the cat command is suitable for viewing files that are not too large. Of course, you can use other commands or methods to view large files in Linux. We will learn about them later.

[Example 1] The cat command itself is very simple, we can directly view the contents of the file. For example:

[root@localhost ~]# cat anaconda-ks.cfg

And if you use the "

-n" option, the line number will be displayed. For example:

[root@localhost ~]# cat -n anaconda-ks.cfg

If you use the "-A" option, it is equivalent to using the "-vET" option. You can view all hidden symbols in the text, including carriage returns. ($), Tab key (^I), etc. For example:

[root@localhost ~]# cat -A anaconda-ks.cfg

[Example 2] Merge the contents of files file1.txt and file2.txt and output them to file file3.txt.

[root@localhost base]# ls
file1.txt    file2.txt
[root@localhost base]# cat file1.txt
http://c.biancheng.net(file1.txt)
[root@localhost base]# cat file2.txt
is great(file2.txt)
[root@localhost base]# cat file1.txt file2.txt > file3.txt
[root@localhost base]# more file3.txt
#more 命令可查看文件中的内容
http://c.biancheng.net(file1.txt)
is great(file2.txt)
[root@localhost base]# ls
file1.txt    file2.txt    file3.txt

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