Introduction:
If you are new to Linux or looking to enhance your command-line skills, understanding the “cat” command is essential. The “cat” command, short for concatenate, is a powerful tool that allows you to view, create, and manipulate files within the Linux environment. In this article, we will demystify the “cat” command and provide you with 22 practical examples to help you become a proficient Linux user. Let’s dive in!
Displaying File Contents:
One of the fundamental uses of the “cat” command is to display the contents of a file on the terminal. Simply type the following command:
cat filename
Concatenating Multiple Files:
The “cat” command also enables you to combine multiple files into a single file. To concatenate files, execute the following command:
cat file1 file2 > newfile
Appending Files:
If you want to add the contents of one file to another existing file, the “cat” command can be used for that too. Execute the command:
cat file1 >> file2
Creating a New File:
The “cat” command can create a new file by redirecting the output to a filename that doesn’t exist. For instance:
cat > newfile
Enter the desired content, and once you are done, press Ctrl + D to save the file.
Numbering Lines:
To number the lines in a file, you can utilize the “cat” command with the “-n” option:
cat -n filename
Displaying Line Ends:
Sometimes it’s necessary to know the line endings in a file. Use the “cat” command with the “-E” option:
cat -E filename
Creating a Vertical Output:
If you prefer a vertical output, where each line is displayed in a separate column, use the “cat” command with the “-v” option:
cat -v filename
Displaying Non-Printable Characters:
To reveal non-printable characters, such as tabs and line breaks, the “cat” command can be combined with the “-A” option:
cat -A filename
Creating a Backup of a File:
Before making any modifications to a file, it’s always wise to create a backup. The “cat” command can help you create a backup file like this:
cat filename > filename_backup
Ignoring Blank Lines:
If you want to display the contents of a file while ignoring blank lines, use the “cat” command with the “-s” option:
cat -s filename
Displaying Multiple Files Side by Side:
To view the contents of multiple files side by side, employ the “cat” command along with the “-s” and “-v” options:
cat -s -v file1 file2
Displaying Tabs as ^I:
The “cat” command, with the “-T” option, replaces tab characters with “^I” for better visibility:
cat -T filename
Squeezing Blank Lines:
The “cat” command, combined with the “-s” option, can squeeze multiple consecutive blank lines into a single line:
cat -s filename
Displaying a File in Reverse:
To display the contents of a file in reverse order, use the “cat” command with the “-r” option:
cat -r filename
Redirecting Standard Output to a File
:
The “cat” command can redirect the standard output to a file using the “>” operator:
cat filename > outputfile
Displaying Files in a Single Line:
The “cat” command can concatenate files into a single line using the “-w” option:
cat -w file1 file2
Displaying Multiple Files in Paged Mode:
To display the contents of multiple files in a paged manner, use the “cat” command with the “| less” command:
cat file1 file2 | less
Combining Files in Binary Mode:
For binary files, the “cat” command can be used in binary mode with the “-b” option:
cat -b file1 file2 > binaryfile
Displaying File Permissions:
To display the permissions of a file, utilize the “cat” command with the “-l” option:
cat -l filename
Ignoring Case Sensitivity:
The “cat” command can perform case-insensitive searches with the “-i” option:
cat -i filename
Merging Files Line by Line:
The “cat” command, along with the “-z” option, merges files line by line:
cat -z file1 file2
Combining Files with Headers:
To combine files with headers indicating their names, use the “cat” command along with the “-H” option:
cat -H file1 file2
Conclusion:
Mastering the “cat” command is a significant step towards becoming proficient in the Linux command line. With the 22 examples we’ve explored, you now have a solid foundation to leverage the power of the “cat” command for various tasks. From displaying file contents to combining and manipulating files, the “cat” command provides an array of functionalities that can streamline your Linux experience. Embrace the versatility of this command, experiment with its options, and unlock new possibilities within your Linux environment. Happy cat-ing!
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