THE CAT COMMAND IN LINUX

Cat(concatenate) command reads data from the file and gives their content as output.

It helps us to create, view, concatenate files.

Here are some of the use cases of the command :

1. Creating a new file:

$ cat >newfile

Creates a new file called newfile

2. Reading a file:

You may have run into this while checking your os type.

$ cat /etc/os-release

On my Os this outputs:

PRETTY_NAME="Debian GNU/Linux 10 (buster)"
NAME="Debian GNU/Linux"
VERSION_ID="10"
VERSION="10 (buster)"
VERSION_CODENAME=buster
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

3. Copy the contents of one file to another file.

$cat [filename-whose-contents-is-to-be-copied] > [destination-filename]

4. View multiple files

$ cat file1 file2

Outputs contents in file1 and file2 .

5. Append the contents of one file to the end of another file

$cat file1 >> file2

Will append contents of file1 to file 2

6. Cat command to open dashed files.

$cat -- "-dashfile"

Will display the content of -dashfile

7. Cat command if the file has a lot of content and can’t fit in the terminal.

$cat "filename" | more

8. Merge the contents of multiple files

$cat "filename1" "filename2" "filename3" > "merged_filename"

Will merge the contents of file in respective order and will insert that content in "merged_filename".

9. Display the content of all html files in the folder.

$cat *.html

Will show the content of all html files present in the folder.

10. Write in an already existing file

$cat >> geeks.txt
The newly added text.

Will append the text "The newly added text." to the end of the file.