CPIO Archive

cpio command is used to process archive files (for example, *.cpio or *.tar files).

cpio stands for “copy in, copy out”.

cpio performs the following three operations.

 ¦Copying files to an archive

 ¦Extracting files from an archive

 ¦Passing files to another directory tree

cpio takes the list of files from the standard input while creating an archive, and sends the output to the standard output.

1. Create *.cpio Archive File

You can create a *.cpio archive that contains files and directories using cpio -ov

[root@server1~]# cd objects

[root@server1~]# ls

 file1.o file2.o file3.o

[root@server1~]# ls | cpio -ov > /tmp/object.cpio

-o     (copy out) cpio -o reads the standard input to obtain a list of path names and copies those files onto the standard output.

-v     Verbose. Print a list of file names. When used with the -t option, the table of contents looks like the output of ls -l command.

As seen above, the ls command passes the three object filenames to cpio command and cpio generates the object.cpio archive.

2. Extract *.cpio Archive File

cpio extract: To extract a given *.cpio file, use cpio -iv as shown below.

[root@server1~]# mkdir output

[root@server1~]# cd output

[root@server1 output]# cpio -idv < /tmp/object.cpio

  -i      (copy in) cpio -i extracts files from the standard input.

  -d     Creates directories as needed

  -v     Verbose. Print a list of file names. When used with the -t option, the table of contents looks like the output of ls -l command.

3. Create *.cpio Archive with Selected Files

The following example creates a *.cpio archive only with *.c files.

[root@server1~]# find . -iname *.c -print | cpio -ov >/tmp/c_files.cpio

-o     (copy out) cpio -o reads the standard input to obtain a list of path names and copies those files onto the standard output.

-v     Verbose. Print a list of file names. When used with the -t option, the table of contents looks like the output of ls -l command.

4. Create *.tar Archive File using cpio -F

We already know how to use the tar command effectively.

Did you know that you can also use cpio command to create tar files as shown below?

[root@server1~]# ls | cpio -ov -H tar -F sample.tar

-o     (copy out) cpio -o reads the standard input to obtain a list of path names and copies those files onto the standard output.

-v     Verbose. Print a list of file names. When used with the -t option, the table of contents looks like the output of ls -l command.

  -H     (header) Read or write header information in header format. Always use this option or the -c option

when the origin and the destination machines are different types (mutually exclusive with -c and -6).

  -F     Archive filename to use instead of standard input or output.

As seen above, instead of redirecting the standard output you can mention the output archive filename with the option -F.

5. Extract *.tar Archive File using cpio command

You can also extract a tar file using cpio command as shown below.

[root@server1~]# cpio -idv -F sample.tar

  -i      (copy in) cpio -i extracts files from the standard input.

  -d     Creates directories as needed

  -v     Verbose. Print a list of file names. When used with the -t option, the table of contents looks like the output of ls -l command.

  -F     Archive filename to use instead of standard input or output.

6. View the content of *.tar Archive File

To view the content of *.tar file, do the following.

[root@server1~]# cpio -it -F sample.tar

  -i      (copy in) cpio -i extracts files from the standard input.

  -t     Print a table of contents of the input. No files are created (mutually exclusive with -V).

  -F     Archive filename to use instead of standard input or output.

7. Create a *.cpio Archive with the Original files that a Symbolic Link Points

cpio archive can be created with the original files that a symbolic link is referring to as shown below.

[root@server1~]# ls | cpio -oLv >/tmp/test.cpio

-o     (copy out) cpio -o reads the standard input to obtain a list of path names and copies those files onto the standard output.

  -L     Follow symbolic links. The default is not to follow symbolic links.

  -v     Verbose. Print a list of file names. When used with the -t option, the table of contents looks like the output of ls -l command.

8. Preserve the File Modification Time while restoring *.cpio

The modification time of the files can be preserved when we are restoring the cpio archive files as shown below.

[root@server1~]# ls | cpio -omv >/tmp/test.cpio

-o     (copy out) cpio -o reads the standard input to obtain a list of path names and copies those files onto the standard output.

-m    Retain previous file modification time. This option is ineffective on directories that are being copied (mutually exclusive with -a).

-v     Verbose. Print a list of file names. When used with the -t option, the table of contents looks like the output of an ls -l command.

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