{"id":59098,"date":"2023-10-16T15:01:14","date_gmt":"2023-10-16T07:01:14","guid":{"rendered":"https:\/\/www.hongkiat.com\/blog\/?p=59098"},"modified":"2023-10-22T15:34:08","modified_gmt":"2023-10-22T07:34:08","slug":"linux-command-cat","status":"publish","type":"post","link":"https:\/\/www.hongkiat.com\/blog\/linux-command-cat\/","title":{"rendered":"How to Use the Cat Command in Linux"},"content":{"rendered":"

The cat<\/code> command, short for \u201cconcatenate,\u201d is a commonly-used tool in Linux, enabling users to view, create, and concentrate files, or redirect their output. In this post, we\u2019ll explore how both new and experienced Linux users can leverage the cat<\/code> command for various tasks.<\/p>\n

The general syntax of the cat<\/code> command is as follow:<\/p>\n

$ cat [OPTION] [FILE]...<\/pre>\n
\n
1. Use cat<\/code> to create a new file and add content<\/h3>\n
cat > filename<\/pre>\n
Example:<\/strong><\/p>\n
The command cat > vegetables.txt<\/code> takes the standard input and redirects it to a file named \u201cvegetables.txt\u201d. When you execute this command, your terminal doesn\u2019t display any output, but instead waits for you to enter text from the keyboard.<\/p>\n
Whatever you type will be written to \u201cvegetables.txt\u201d. To finish and save the file, you\u2019ll need to press CTRL-D<\/code> (or CTRL-Z<\/code> on Windows systems using some terminal applications).<\/p>\n
Here\u2019s an example of how you might use it:<\/p>\n
$ cat > vegetables.txt\r\nCarrot\r\nBroccoli\r\nSpinach\r\n^D<\/pre>\n
At this point, a file named \u201cvegetables.txt\u201d would be created with the following content:<\/p>\n
Carrot\r\nBroccoli\r\nSpinach<\/pre>\n
\n
2. Display file\u2019s content with cat<\/code><\/h3>\n
cat filename<\/pre>\n
Example:<\/strong><\/p>\n
Assume the file contains a list of common vegetables; executing the command cat vegetables.txt<\/code> would display the contents of the file in the terminal.<\/p>\n
Carrots\r\nBroccoli\r\nSpinach\r\nTomatoes\r\nCucumbers\r\nPeppers\r\nOnions\r\nPotatoes\r\nKale\r\nLettuce<\/pre>\n
\n
3. Display content of multiple files with cat<\/code><\/h3>\n
cat filename_1 filename_2<\/pre>\n
Example:<\/p>\n
Assuming the contents of the files fruits.txt and vegetables.txt are respectively as follows:<\/p>\n
Apple\r\nBanana\r\nCherry\r\n<\/pre>\n
Carrot\r\nLettuce\r\nTomato\r\n<\/pre>\n
The command cat fruits.txt vegetables.txt<\/code> would produce:<\/p>\n
Apple\r\nBanana\r\nCherry\r\nCarrot\r\nLettuce\r\nTomato\r\n<\/pre>\n
\n
4. Display content with line numbering with cat<\/code><\/h3>\n
cat -n filename<\/pre>\n
Example:<\/strong><\/p>\n
If the contents of fruits.txt<\/code> are the same as in the previous example:<\/p>\n
Apple\r\nBanana\r\nCherry\r\n<\/pre>\n
Then the command cat -n fruits.txt<\/code> would produce:<\/p>\n
\r\n     1\tApple\r\n     2\tBanana\r\n     3\tCherry\r\n<\/pre>\n
\n
5. Copy, replace, or replicate a file\u2019s content using cat<\/code><\/h3>\n
cat filename new_filename<\/pre>\n
Example:<\/strong><\/p>\n
The command cat fruits.txt > new_fruits.txt<\/code> will take the contents of fruits.txt<\/code> and write them into a new file named new_fruits.txt<\/code>. This command won\u2019t display any output to the terminal, assuming it executes successfully.<\/p>\n
If fruits.txt<\/code> has the same content as before:<\/p>\n
Apple\r\nBanana\r\nCherry\r\n<\/pre>\n
After running the command, the content of new_fruits.txt<\/code> will be:<\/p>\n
Apple\r\nBanana\r\nCherry\r\n<\/pre>\n
\n
6. Merge multiple files\u2019 content into one with cat<\/code><\/h3>\n
cat filename_1 filename_2 > filename_3<\/pre>\n
Example:<\/strong><\/p>\n
The command cat fruits.txt vegetable.txt > grocery.txt<\/code> will concatenate the contents of fruits.txt<\/code> and vegetable.txt<\/code>, then redirect the output to a file called grocery.txt<\/code>. If either of the input files doesn\u2019t exist, an error message will be displayed in the terminal, but you won\u2019t see the concatenated contents in the terminal because they are being redirected to grocery.txt<\/code>.<\/p>\n
Suppose fruits.txt<\/code> contains:<\/p>\n
Apple\r\nBanana\r\nCherry\r\n<\/pre>\n
And vegetable.txt<\/code> contains:<\/p>\n
Carrot\r\nLettuce\r\nTomato\r\n<\/pre>\n
After running the command, the terminal won\u2019t show any output (unless there\u2019s an error), but the file grocery.txt<\/code> will contain:<\/p>\n
Apple\r\nBanana\r\nCherry\r\nCarrot\r\nLettuce\r\nTomato\r\n<\/pre>\n
If vegetable.txt<\/code> was misspelled or doesn\u2019t exist, you would see an error in the terminal similar to:<\/p>\n
cat: vegetable.txt: No such file or directory\r\n<\/pre>\n
\n
More Linux commands:<\/h3>\n\n\n\n\n\n\n\n\n\n
Directory Operations<\/td>\nrmdir<\/code><\/a> \u00b7 cd<\/code><\/a> \u00b7 pwd<\/code><\/a> \u00b7 exa<\/code><\/a> \u00b7 ls<\/code><\/a><\/td>\n<\/tr>\n
File Operations<\/td>\ncat<\/code><\/a> \u00b7 cp<\/code><\/a> \u00b7 dd<\/code><\/a> \u00b7 less<\/code><\/a> \u00b7 touch<\/code><\/a> \u00b7 ln<\/code><\/a> \u00b7 rename<\/code><\/a> \u00b7 more<\/code><\/a> \u00b7 head<\/code><\/a><\/td>\n<\/tr>\n
File System Operations<\/td>\nchown<\/code><\/a> \u00b7 mkfs<\/code><\/a> \u00b7 locate<\/code><\/a><\/td>\n<\/tr>\n
Networking<\/td>\nping<\/code><\/a> \u00b7 curl<\/code><\/a> \u00b7 wget<\/code><\/a> \u00b7 iptables<\/code><\/a> \u00b7 mtr<\/code><\/a><\/td>\n<\/tr>\n
Search and Text Processing<\/td>\nfind<\/code><\/a> \u00b7 grep<\/code><\/a> \u00b7 sed<\/code><\/a> \u00b7 whatis<\/code><\/a> \u00b7 ripgrep<\/code><\/a> \u00b7 fd<\/code><\/a> \u00b7 tldr<\/code><\/a><\/td>\n<\/tr>\n
System Information and Management<\/td>\nenv<\/code><\/a> \u00b7 history<\/code><\/a> \u00b7 top<\/code><\/a> \u00b7 who<\/code><\/a> \u00b7 htop<\/code><\/a> \u00b7 glances<\/code><\/a> \u00b7 lsof<\/code><\/a><\/td>\n<\/tr>\n
User and Session Management<\/td>\nscreen<\/code><\/a> \u00b7 su<\/code><\/a> \u00b7 sudo<\/code><\/a> \u00b7 open<\/code><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>","protected":false},"excerpt":{"rendered":"
Understand the ‘cat’ command in Linux more. This guide offers insights into viewing, creating, and concentrating files, ensuring you leverage its full potential.<\/p>\n","protected":false},"author":9,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[3397],"tags":[888,3316],"topic":[],"class_list":["entry-content","is-maxi"],"acf":[],"yoast_head":"\nHow to Use the Cat Command in Linux - Hongkiat<\/title>\n<meta name=\"description\" content=\"Understand the 'cat' command in Linux more. 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