To join two or more text files on the Linux command-line, you can use the cat command. The cat (short for “concatenate”) command is one of the most commonly used commands in Linux as well as other UNIX-like operating systems, used to concatenate files and print on the standard output.
It is not only used to view files but can also be used to create files together with the redirection character.
View Contents of File in Linux
To view the contents of a file without opening it, you can use the cat command as shown (remember to replace domains.txt and domains2.txt with the names of the files you wish to combine):
[abhi@linuxshelltips:~]$ cat domains.txt tecmint.com cyberciti.biz [abhi@linuxshelltips:~]$ cat domains2.txt linuxshelltips.com google.com
Join Contents of Two Files in Linux
To join or combine the two files and view them as one on the terminal, run the following command:
[abhi@linuxshelltips:~]$ cat domains.txt domains2.txt tecmint.com cyberciti.biz linuxshelltips.com google.com
You can also join three or more files, for example:
[abhi@linuxshelltips:~]$ cat file1 file2 file3 OR [abhi@linuxshelltips:~]$ cat file1 file2 file3 file4
After joining files, you can save the output in a single file using the redirection character like the following:
[abhi@linuxshelltips:~]$ cat domains.txt domains2.txt > domains_all.txt [abhi@linuxshelltips:~]$ cat domains_all.txt
Also, you can join two or more files and append(add) their output to an existing file. For example:
[abhi@linuxshelltips:~]$ cat file1 file2 >> domains_all.txt
Merge Contents of Two Files Using Sed Command
Alternatively, you can also use the popular sed (a streamer editor) to join or merge the content of two or more files on the command-line, by using its r flag, which instructs sed to read the file provided as an argument. If there are many files, it reads all of them and displays their content as a combined output.
[abhi@linuxshelltips:~]$ sed r domains.txt domains2.txt [abhi@linuxshelltips:~]$ sed r domains.txt domains2.txt > sed_out.txt [abhi@linuxshelltips:~]$ cat sed_out.txt
If you have any other questions about this topic, do not hesitate to ask for help in the comments section.