Create tar archive of a directory, except for hidden files?

Question

I'm wanting to create a tar archive of a specific directory (with its subdirectories of course). But when I do it, using the tar command, I get a list of files that were included, for example:

a calendar_final/._style.css

a calendar_final/style.css

As you can see, there are two versions of the same file. This goes for every file, and there are many. How do I exclude the temporary files, with the ._ prefix, from the tar archive?

Answer 1

You posted in a comment that you are working on a Mac OS X system. This is an important clue to the purpose of these ._* files.

These ._* archive entries are chunks of AppleDouble data that contain the extra information associated with the corresponding file (the one without the ._ prefix). They are generated by the Mac OS X–specific copyfile(3) family of functions. The AppleDouble blobs store access control data (ACLs) and extended attributes (commonly, Finder flags and “resource forks”, but xattrs can be used to store any kind of data).

The system-supplied Mac OS X archive tools (bsdtar (also symlinked as tar), gnutar, and pax) will generate a ._* archive member for any file that has any extended information associated with it; in “unarchive” mode, they will also decode those archive members and apply the resulting extended information to the associated file. This creates a “full fidelity” archive for use on Mac OS X systems by preserving and later extracting all the information that the HFS+ filesystem can store.

The corresponding archive tools on other systems do not know to give special handling to these ._* files, so they are unpacked as normal files. Since such files are fairly useless on other systems, they are often seen as “junk files”. Correspondingly, if a non–Mac OS X system generates an archive that includes normal files that start with ._, the Mac OS X unarchiving tools will try to decode those files as extended information.

There is, however an undocumented(?) way to make the system-supplied Mac OS X archivers behave like they do on other Unixy systems: the COPYFILE_DISABLE environment variable. Setting this variable (to any value, even the empty string), will prevent the archivers from generating ._* archive members to represent any extended information associated with the archived files. Its presence will also prevent the archivers from trying to interpret such archive members as extended information.

COPYFILE_DISABLE=1 tar czf new.tar.gz …
COPYFILE_DISABLE=1 tar xzf unixy.tar.gz …

You might set this variable in your shell’s initialization file if you want to work this way more often than not.

# disable special creation/extraction of ._* files by tar, etc. on Mac OS X
COPYFILE_DISABLE=1; export COPYFILE_DISABLE

Then, when you need to re-enable the feature (to preserve/restore the extended information), you can “unset” the variable for individual commands:

(unset COPYFILE_DISABLE; tar czf new-osx.tar.gz …)

---

The archivers on Mac OS X 10.4 also do something similar, though they use a different environment variable: COPY_EXTENDED_ATTRIBUTES_DISABLE

Answer 2

This should work:

tar zcf calendar.tgz "a calendar_final" --exclude '.*'

Answer 3

Frederik Deweerdt has given a solution that works on GNU tar (used on Linux, Cygwin, FreeBSD, OSX, possibly others), but not on other systems such as NetBSD, OpenBSD or Solaris.

POSIX doesn't specify the tar command (because it varies too wildly between unix variants) and introduces the pax command instead. The option -w means to produce an archive (-r extracts), and -x selects the archive format. The option -s '!BRE!!' excludes all files whose path matches the basic regular expression BRE.

pax -w -x ustar -s '!^.*/\..*$!!' calendar_final >calendar_final.tar

Answer 4

As of bsdtar 3.0.3 - libarchive 3.0.3 (and perhaps earlier) there's a new (Mac OS X specific) option to the bsdtar command called --disable-copyfile to suppress the creation of ._ files. Older versions of tar don't have the --disable-copyfile option, but setting the environment variable COPYFILE_DISABLE=1 should work.

Answer 5

The modern version of this would be to create the tarball using the --no-xattrs flag for MacOS's BSD tar.

tar --no-xattrs -c -f <tarfilename> [file list/glob/whatever]

Answer 6

Follow these steps:

1. Find all ._ files and list them using -ls so that you can see all ._ files and finally delete them.

   find /path/to/directory -type f -iname "._*.*" -ls -delete
   

2. Create archive .tar using.

   tar -cvf name.tar /path/to/directory
   

Answer 7

Nothing worked, in my case these hidden files is not present in file system (they metadata), so, I can't delete or ignore them. Solution I found is: --no-mac-metadata

To create archive in MacOS

# --no-xattrs - to fix warning when extracting on non-MacOS:
#   tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.provenance'
#
# --no-mac-metadata - to not add Apple specific file attributes.
#   produces `._{filename}` files while extracting on non MacOS
tar -c \
    --no-xattrs \
    --no-mac-metadata \
     -f ${TARBALL} *

Note:

As I use in automated script, just in case I try to delete all useless files before creating .tar, this can be replaced with tar inclusion/exclusion rules, I just find it easy to read this way.

# remove annoying Apple files (._*) and remove python caches
find . \
    -type f -name '._*' -delete -or \
    -type f -name '*.py[co]' -delete -or \
    -type d -name __pycache__ -delete