GNU tar

https://www.gnu.org/software/tar/manual/html_node/
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GNU tar is an archiving utility used to create, extract, and manipulate tar archives for file...
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### tar-snapshot-edit: Example session showing inspection and update

Source: https://www.gnu.org/software/tar/manual/html_node/Fixing-Snapshot-Files.html

Example session demonstrating how to inspect device numbers in two snapshot files and then update them using the -b and -r options. The -b option creates a backup copy of the snapshot file, and -r takes a comma-separated list of olddev-newdev pairs.

```shell
$ `tar-snapshot-edit root_snap.0 boot_snap.0`
File: root_snap.0
  Detected snapshot file version: 2

  Device 0x0000 occurs 1 times.
  Device 0x0003 occurs 1 times.
  Device 0x0005 occurs 1 times.
  Device 0x0013 occurs 1 times.
  Device 0x6801 occurs 1 times.
  Device 0x6803 occurs 6626 times.
  Device 0xfb00 occurs 1 times.

File: boot_snap.0
  Detected snapshot file version: 2

  Device 0x6801 occurs 3 times.

```

```shell
$ `tar-snapshot-edit -b -r 0x6801-0x6901,0x6803-0x6903 root_snap.0 boot_snap.0`
File: root_snap.0
  Detected snapshot file version: 2

  Updated 6627 records.

File: boot_snap.0
  Detected snapshot file version: 2

  Updated 3 records.

```

--------------------------------

### Simplified example without explicit --recursion

Source: https://www.gnu.org/software/tar/manual/html_node/Position_002dSensitive-Options.html

A footnote clarifies that --recursion is the default and can be omitted. The same example can be written without it.

```shell
tar -cf a.tar /usr --no-recursion /var/*
```

--------------------------------

### opt-doc-col example: adjusting help output column

Source: https://www.gnu.org/software/tar/manual/html_node/Configuring-Help-Summary.html

Shows how setting ARGP_HELP_FMT=opt-doc-col changes the column where option descriptions start. Default is 29. If the value is too small, the description wraps to a separate line.

```shell
$ `tar --help|grep ARCHIVE`
  -f, --file=ARCHIVE         use archive file or device ARCHIVE
$ `ARGP_HELP_FMT=opt-doc-col=19 tar --help|grep ARCHIVE`
  -f, --file=ARCHIVE   use archive file or device ARCHIVE
$ `ARGP_HELP_FMT=opt-doc-col=9 tar --help|grep ARCHIVE`
  -f, --file=ARCHIVE
           use archive file or device ARCHIVE
```

--------------------------------

### tar --create --verbose example

Source: https://www.gnu.org/software/tar/manual/html_node/create-verbose.html

Use the --verbose (-v) option with tar --create to list files as they are archived. The example shows the command and its output, which lists each file name on a separate line.

```shell
$ `tar --create --verbose --file=collection.tar blues folk jazz`
blues
folk
jazz
```

--------------------------------

### Example of split member names

Source: https://www.gnu.org/software/tar/manual/html_node/Split-Recovery.html

Example showing the member names when var/longfile is split across three volumes.

```text
var/longfile
var/GNUFileParts/longfile.1
var/GNUFileParts/longfile.2
```

--------------------------------

### tar -c --checkpoint=1000 /var

Source: https://www.gnu.org/software/tar/manual/html_node/checkpoints.html

Equivalent to the previous example because echo is the default action.

```shell
$ `tar -c --checkpoint=1000` /var

```

--------------------------------

### Example dd command for extended header extraction

Source: https://www.gnu.org/software/tar/manual/html_node/Sparse-Recovery.html

Concrete example of the dd command using the values from the earlier listing.

```shell
$ `dd if=arc.tar of=xhdr bs=512 skip=56 count=7`
```

--------------------------------

### restore --level=1 - start restore from level 1 backup

Source: https://www.gnu.org/software/tar/manual/html_node/Scripted-Restoration.html

Starts restoring from the given backup level (1) instead of the default level 0, useful when only recent backups are needed.

```shell
restore --level=1

```

--------------------------------

### ARGP_HELP_FMT boolean variable assignment examples

Source: https://www.gnu.org/software/tar/manual/html_node/Configuring-Help-Summary.html

Shows how to set a boolean variable to true (by naming it) or false (by prefixing with 'no-').

```text
# Assign true value:
dup-args
# Assign false value:
no-dup-args

```

--------------------------------

### Strip two leading directory components

Source: https://www.gnu.org/software/tar/manual/html_node/transform.html

Example 2: strips two leading directory components, equivalent to --strip-components=2.

```shell
$ `tar --transform='s,/*[^/]*/[^/]*/,,' -x -f arch.tar`

```

--------------------------------

### doc-opt-col example: help output with doc-opt-col=6

Source: https://www.gnu.org/software/tar/manual/html_node/Configuring-Help-Summary.html

Shows the effect of setting doc-opt-col to 6, which shifts the doc options (format names) to column 6.

```text
  -H, --format=FORMAT        create archive of the given format.

 FORMAT is one of the following:

        gnu                      GNU tar 1.13.x format
        oldgnu                   GNU format as per tar <= 1.12
        pax                      POSIX 1003.1-2001 (pax) format
        posix                    same as pax
        ustar                    POSIX 1003.1-1988 (ustar) format
        v7                       old V7 tar format

```

--------------------------------

### Example UID translation map file

Source: https://www.gnu.org/software/tar/manual/html_node/override.html

A sample configuration file for the --owner-map option, demonstrating mapping of UID 10 to 'bin' and 'smith' to 'root' with UID 0.

```text
+10     bin
smith   root:0

```

--------------------------------

### tar --verbose --acls detailed listing

Source: https://www.gnu.org/software/tar/manual/html_node/Extended-File-Attributes.html

Example output when listing with two or more --verbose options and --acls. The ACL is printed after each file entry, starting with 'a:'.

```text
-rw-r--r--+ smith/users      110 2016-03-16 16:07 file
  a: user::rw-,user:gray:-w-,group::r--,mask::rw-,other::r--

```

--------------------------------

### doc-opt-col example: default help output for --format

Source: https://www.gnu.org/software/tar/manual/html_node/Configuring-Help-Summary.html

Shows the default layout of the help output for the --format option, where format names are doc options.

```text
  -H, --format=FORMAT        create archive of the given format.

 FORMAT is one of the following:

    gnu                      GNU tar 1.13.x format
    oldgnu                   GNU format as per tar <= 1.12
    pax                      POSIX 1003.1-2001 (pax) format
    posix                    same as pax
    ustar                    POSIX 1003.1-1988 (ustar) format
    v7                       old V7 tar format

```

--------------------------------

### tar --verbose --xattrs detailed listing

Source: https://www.gnu.org/software/tar/manual/html_node/Extended-File-Attributes.html

Example output when listing with two or more --verbose options and --xattrs. Each extended attribute is listed on a separate line starting with two spaces and 'x:' followed by length and name.

```text
-rw-r--r--* smith/users      110 2016-03-16 16:07 file
  x:  7 user.mime_type
  x: 32 trusted.md5sum

```

--------------------------------

### tar --verify -cf /tmp/foo.tar /etc

Source: https://www.gnu.org/software/tar/manual/html_node/verify.html

Example command showing the use of --verify with --create. Note that tar strips leading slashes, so this works as desired only if the working directory is /.

```shell
tar --verify -cf /tmp/foo.tar /etc
```

--------------------------------

### tar --create --verbose --blocking-factor=20 --file=/dev/rmt0

Source: https://www.gnu.org/software/tar/manual/html_node/Long-Options.html

Example of using long options with arguments, demonstrating the --file option with an equal sign.

```shell
$ `tar --create --verbose --blocking-factor=20 --file=/dev/rmt0`
```

--------------------------------

### Create a multi-volume archive with --tape-length (G)

Source: https://www.gnu.org/software/tar/manual/html_node/Multi_002dVolume-Archives.html

Equivalent to the previous example, but uses the 'G' suffix to specify the tape length in gigabytes. This also automatically selects --multi-volume.

```shell
$ `tar --create --tape-length=4G --file=/dev/tape files`
```

--------------------------------

### Format 2 format identifier example

Source: https://www.gnu.org/software/tar/manual/html_node/Snapshot-Files.html

Example of the format identifier line in a format 2 snapshot file, showing the GNU tar version and format version.

```text
GNU tar-1.35.90-2

```

--------------------------------

### Create archive of directory with tar --create --verbose --file

Source: https://www.gnu.org/software/tar/manual/html_node/create-dir.html

Creates an archive named music.tar containing the practice directory. The --verbose flag lists files as they are added.

```shell
$ `tar --create --verbose --file=music.tar practice`
```

--------------------------------

### Output of tar --create --verbose --file=music.tar practice

Source: https://www.gnu.org/software/tar/manual/html_node/create-dir.html

Shows the expected output when archiving the practice directory. The archive file collection.tar is also included because it is inside the directory.

```shell
practice/
practice/blues
practice/folk
practice/jazz
practice/collection.tar
```

--------------------------------

### Prepend /prefix/ to each file name

Source: https://www.gnu.org/software/tar/manual/html_node/transform.html

Example 4: prepends /prefix/ to each file name during extraction.

```shell
$ `tar --transform 's,^,/prefix/,' -x -f arch.tar`

```

--------------------------------

### tar --owner=root example

Source: https://www.gnu.org/software/tar/manual/html_node/override.html

Forces the owner of archive members to the user name root.

```shell
$ `tar -c -f archive.tar --owner=root .`

```

--------------------------------

### Use -C option in file list to change directories

Source: https://www.gnu.org/software/tar/manual/html_node/files.html

Shows a file list (list) that uses -C to switch to /etc and /lib, and the tar command that creates foo.tar from it. The resulting archive contains passwd, hosts, and libc.a.

```shell
$ `cat list`
-C/etc
passwd
hosts
-C/lib
libc.a
$ `tar -c -f foo.tar --files-from list`

```

--------------------------------

### Create archives bluesrock.tar and folkjazz.tar

Source: https://www.gnu.org/software/tar/manual/html_node/concatenate.html

Creates two small archives from the practice files. The first command creates bluesrock.tar from files 'blues' and 'rock'; the second creates folkjazz.tar from 'folk' and 'jazz'. Output shows the member names as they are added.

```shell
$ `tar -cvf bluesrock.tar blues rock`
blues
rock
$ `tar -cvf folkjazz.tar folk jazz`
folk
jazz
```

--------------------------------

### Verbose output for a specific member

Source: https://www.gnu.org/software/tar/manual/html_node/list.html

Example verbose output showing owner, size, and date for the member.

```shell
-rw-r--r-- myself/user      62 1990-05-23 10:55 folk

```

--------------------------------

### Copy directory hierarchy with long options and -C

Source: https://www.gnu.org/software/tar/manual/html_node/copy-directory-hierarchy.html

Same as the second example but using long option forms (--directory, --create, --file, --extract) with -C.

```shell
$ `tar --directory sourcedir --create --file=- . \
       | tar --directory targetdir --extract --file=-`
```

--------------------------------

### tar --owner=0 example

Source: https://www.gnu.org/software/tar/manual/html_node/override.html

Forces the owner of archive members to user ID 0 (root).

```shell
$ `tar -c -f archive.tar --owner=0 .`

```

--------------------------------

### tar --help output excerpt showing main operation mode options

Source: https://www.gnu.org/software/tar/manual/html_node/Configuring-Help-Summary.html

Shows the default layout of the help summary, with short options, long options, and descriptions. This is the output that can be customized via ARGP_HELP_FMT.

```text
 Main operation mode:

  -A, --catenate, --concatenate   append tar files to an archive
  -c, --create               create a new archive
  -d, --diff, --compare      find differences between archive and
                             file system
      --delete               delete from the archive

```

--------------------------------

### Extract usr/ hierarchy into usr/local/

Source: https://www.gnu.org/software/tar/manual/html_node/transform.html

Example 1: extracts the usr/ hierarchy into usr/local/ using a transform expression.

```shell
$ `tar --transform='s,usr/,usr/local/,' -x -f arch.tar`

```

--------------------------------

### Multiple checkpoint actions with echo, sleep, and exec

Source: https://www.gnu.org/software/tar/manual/html_node/checkpoints.html

Combines multiple --checkpoint-action options in one command. This example displays two messages, pauses for 30 seconds, and executes /sbin/cpoint. It also shows that --checkpoint-action can be used without --checkpoint, in which case the default frequency (every 10th record) is used.

```shell
$ `tar -c -f arc.tar \
       --checkpoint-action='\aecho=Hit %s checkpoint #%u' \
       --checkpoint-action='echo=Sleeping for 30 seconds' \
       --checkpoint-action='sleep=30' \
       --checkpoint-action='exec=/sbin/cpoint'`
```

--------------------------------

### tar -c -v -b 20 -f /dev/rmt0

Source: https://www.gnu.org/software/tar/manual/html_node/Short-Options.html

Example of separated short options with arguments directly following each option that requires one. Demonstrates the standard Unix style for tar commands.

```shell
$ `tar -c -v -b 20 -f /dev/rmt0`
```

--------------------------------

### Output of tar --list for collection.tar

Source: https://www.gnu.org/software/tar/manual/html_node/list.html

Example output showing the member names listed by the previous command.

```shell
blues
folk
jazz

```

--------------------------------

### Warnings for non-PAX-aware tar

Source: https://www.gnu.org/software/tar/manual/html_node/Split-Recovery.html

Example warnings and file extractions when using a tar implementation that is not PAX-aware. These warnings can be ignored.

```shell
$ `tar xf vol-1.tar`
var/PaxHeaders/longfile: Unknown file type 'x', extracted as
normal file
Unexpected EOF in archive
$ `tar xf vol-2.tar`
tmp/GlobalHead.1: Unknown file type 'g', extracted as normal file
GNUFileParts/PaxHeaders/sparsefile.1: Unknown file type
'x', extracted as normal file
```
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