Add files to archive linux

How to add/update a file to an existing tar.gz archive?

Is there a way to add/update a file in a tar.gz archive? Basically, I have an archive which contains a file at /data/data/com.myapp.backup/./files/settings.txt and I’d like to pull that file from the archive (already done) and push it back into the archive once the edit has been done. How can I accomplish this? Is it problematic because of the . in the path?

+1. This would make working on OS X so easy. Currently, I have to hand clean a directory of all the hidden files like .DS_Store and then re-tar the directory.

5 Answers 5

To pull your file from your archive, you can use tar xzf archive.tar.gz my/path/to/file.txt . Note that the directories in the file’s path will be created as well. Use tar t (i.e. tar tzf archive.tar.gz ) to list the files in the archive.

tar does not support «in-place» updating of files. However, you can add files to the end of an archive, even if they have the same path as a file already in the archive. In that case, both copies of the file will be in the archive, and the file added later will override the earlier one. The command to use for this is tar r (or tar u to only add files that are newer than the archive) is the command to use. The . in the path should not be a problem.

There is a catch, though: you can’t add to a compressed archive. So you would have to do:

gunzip archive.tar.gz tar rf archive.tar data/data/com.myapp.backup/./files/settings.txt gzip archive.tar 

Which is probably not what you want to hear, since it means rewriting the entire archive twice over. If it’s not a very large archive, it might be better to untar the whole thing and then re-tar it after editing. Alternately, you could use an uncompressed archive.

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10 “tar” Command Examples in Linux to Create and Extract Archives

The tar (tape archive) command is used to create and extract archives in Linux. It can compress and store multiple files in a single archive.

The commonly seen file extensions are .tar.gz and .tar.bz2 which is a tar archive further compressed using gzip or bzip algorithms respectively.

In this tutorial we shall take a look at simple examples of using the tar command to do daily jobs of creating and extracting archives on linux desktops or servers.

Using the tar command

The tar command is available by default on most linux systems and you do not need to install it separately.

With tar there are 2 compression formats, gzip and bzip. The "z" option specifies gzip and "j" option specifies bzip. It is also possible to create uncompressed archives.

1. Extract a tar.gz archive

Well, the more common use is to extract tar archives. The following command shall extract the files out a tar.gz archive

Here is a quick explanation of the parameters used —

• x — Extract files
• v — verbose, print the file names as they are extracted one by one
• z — The file is a «gzipped» file
• f — Use the following tar archive for the operation

Those are some of the important options to memorise

Extract tar.bz2/bzip archives

Files with extension bz2 are compressed with the bzip algorithm and tar command can deal with them as well. Use the j option instead of the z option.

$ tar -xvjf archivefile.tar.bz2

2. Extract files to a specific directory or path

To extract out the files to a specific directory, specify the path using the «-C» option. Note that its a capital C.

$ tar -xvzf abc.tar.gz -C /opt/folder/

However first make sure that the destination directory exists, since tar is not going to create the directory for you and will fail if it does not exist.

3. Extract a single file

To extract a single file out of an archive just add the file name after the command like this

$ tar -xz -f abc.tar.gz "./new/abc.txt"

More than once file can be specified in the above command like this

$ tar -xv -f abc.tar.gz "./new/cde.txt" "./new/abc.txt"

4. Extract multiple files using wildcards

Wildcards can be used to extract out a bunch of files matching the given wildcards. For example all files with «.txt» extension.

$ tar -xv -f abc.tar.gz --wildcards "*.txt"

5. List and search contents of the tar archive

If you want to just list out the contents of the tar archive and not extract them, use the «-t» option. The following command prints the contents of a gzipped tar archive,

$ tar -tz -f abc.tar.gz ./new/ ./new/cde.txt ./new/subdir/ ./new/subdir/in.txt ./new/abc.txt .

Pipe the output to grep to search a file or less command to browse the list. Using the «v» verbose option shall print additional details about each file.

For tar.bz2/bzip files use the «j» option

Use the above command in combination with the grep command to search the archive. Simple!

$ tar -tvz -f abc.tar.gz | grep abc.txt -rw-rw-r-- enlightened/enlightened 0 2015-01-13 11:40 ./new/abc.txt

6. Create a tar/tar.gz archive

Now that we have learnt how to extract existing tar archives, its time to start creating new ones. The tar command can be told to put selected files in an archive or an entire directory. Here are some examples.

The following command creates a tar archive using a directory, adding all files in it and sub directories as well.

$ tar -cvf abc.tar ./new/ ./new/ ./new/cde.txt ./new/abc.txt

The above example does not create a compressed archive. Just a plain archive, that puts multiple files together without any real compression.

In order to compress, use the «z» or «j» option for gzip or bzip respectively.

The extension of the file name does not really matter. "tar.gz" and tgz are common extensions for files compressed with gzip. ".tar.bz2" and ".tbz" are commonly used extensions for bzip compressed files.

7. Ask confirmation before adding files

A useful option is «w» which makes tar ask for confirmation for every file before adding it to the archive. This can be sometimes useful.

Only those files would be added which are given a yes answer. If you do not enter anything, the default answer would be a «No».

# Add specific files $ tar -czw -f abc.tar.gz ./new/* add ‘./new/abc.txt’?y add ‘./new/cde.txt’?y add ‘./new/newfile.txt’?n add ‘./new/subdir’?y add ‘./new/subdir/in.txt’?n # Now list the files added $ tar -t -f abc.tar.gz ./new/abc.txt ./new/cde.txt ./new/subdir/

8. Add files to existing archives

The r option can be used to add files to existing archives, without having to create new ones. Here is a quick example

Files cannot be added to compressed archives (gz or bzip). Files can only be added to plain tar archives.

9. Add files to compressed archives (tar.gz/tar.bz2)

Its already mentioned that its not possible to add files to compressed archives. However it can still be done with a simple trick. Use the gunzip command to uncompress the archive, add file to archive and compress it again.

$ gunzip archive.tar.gz $ tar -rf archive.tar ./path/to/file $ gzip archive.tar

For bzip files use the bzip2 and bunzip2 commands respectively.

10. Backup with tar

A real scenario is to backup directories at regular intervals. The tar command can be scheduled to take such backups via cron. Here is an example —

$ tar -cvz -f archive-$(date +%Y%m%d).tar.gz ./new/

Run the above command via cron and it would keep creating backup files with names like —
‘archive-20150218.tar.gz’.

Ofcourse make sure that the disk space is not overflown with larger and larger archives.

11. Verify archive files while creation

The «W» option can be used to verify the files after creating archives. Here is a quick example.

$ tar -cvW -f abc.tar ./new/ ./new/ ./new/cde.txt ./new/subdir/ ./new/subdir/in.txt ./new/newfile.txt ./new/abc.txt Verify ./new/ Verify ./new/cde.txt Verify ./new/subdir/ Verify ./new/subdir/in.txt Verify ./new/newfile.txt Verify ./new/abc.txt

Note that the verification cannot be done on compressed archives. It works only with uncompressed tar archives.

Conclusion

Besides the tar command, there are many other commands available on the linux command line that can be used to compress and pack files in an archive. For example the zip and unzip command can also be used to create compressed archives.

The zip command also supports the zipcloak command that can be used to create password protected .zip archives. The tar format does not support any kind of encryption. If you want to create password protected tar archives then use the ccrypt command to encrypt the .tar or .tar.gz file.

Thats all for now. For more check out the man page for tar command, with «man tar». Or run the «tar —help» to see the list of all options supported by the tar command.

A Tech Enthusiast, Blogger, Linux Fan and a Software Developer. Writes about Computer hardware, Linux and Open Source software and coding in Python, Php and Javascript. He can be reached at [email protected] .

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Add files to archive linux

The simplest way to add a file to an already existing archive is the ‘ —append ’ (‘ -r ’) operation, which writes specified files into the archive whether or not they are already among the archived files.

When you use ‘ —append ’, you must specify file name arguments, as there is no default. If you specify a file that already exists in the archive, another copy of the file will be added to the end of the archive. As with other operations, the member names of the newly added files will be exactly the same as their names given on the command line. The ‘ —verbose ’ (‘ -v ’) option will print out the names of the files as they are written into the archive.

‘ —append ’ cannot be performed on some tape drives, unfortunately, due to deficiencies in the formats those tape drives use. The archive must be a valid tar archive, or else the results of using this operation will be unpredictable. See section Tapes and Other Archive Media.

To demonstrate using ‘ —append ’ to add a file to an archive, create a file called ‘rock’ in the ‘practice’ directory. Make sure you are in the ‘practice’ directory. Then, run the following tar command to add ‘rock’ to ‘collection.tar’:

$ tar --append --file=collection.tar rock 

If you now use the ‘ —list ’ (‘ -t ’) operation, you will see that ‘rock’ has been added to the archive:

$ tar --list --file=collection.tar -rw-r--r-- me/user 28 1996-10-18 16:31 jazz -rw-r--r-- me/user 21 1996-09-23 16:44 blues -rw-r--r-- me/user 20 1996-09-23 16:44 folk -rw-r--r-- me/user 20 1996-09-23 16:44 rock

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