using TAR to backup a home directory
Script started on Wed 28 Jan 2015 10:03:45 AM PST
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The following commands demonstrates the creation of a TAR file of the home
directory in order to reimage a Linux system, or to make a backup copy.
Because of the size of the home directory on the real system a /home2/test
directory was created for the demonstration. Also note where sudo or admin
rights were required. A user can backup their own home directory, but not
all of /home.
one would mount an external memory stick or drive, or copy the tar file
to a different disk or device in order to update the systme. If /home
is a separate file system mounted by the system upgrades and reinstallations
are less trouble.
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--> du -sh /home
du: cannot read directory /home/lost+found: Permission denied
142G /home
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--> ll /home
total 20
drwx------ 2 root root 16384 Jun 18 2014 lost+found
drwxr-xr-x 39 luser users 4096 Jan 21 12:17 luser
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--> sudo mkdir /home2/test
mkdir: cannot create directory /home2/test: No such file or directory
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--> mkdir --help
Usage: mkdir [OPTION]... DIRECTORY...
Create the DIRECTORY(ies), if they do not already exist.
Mandatory arguments to long options are mandatory for short options too.
-m, --mode=MODE set file mode (as in chmod), not a=rwx - umask
-p, --parents no error if existing, make parent directories as needed
-v, --verbose print a message for each created directory
-Z, --context=CTX set the SELinux security context of each created
directory to CTX
--help display this help and exit
--version output version information and exit
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--> sudo touch /home2/test/this-is-a-file.txt
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--> ll /home2
total 4
drwxr-xr-x 2 root root 4096 Jan 28 10:05 test
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--> ll /home2/test
total 0
-rw-r--r-- 1 root root 0 Jan 28 10:05 this-is-a-file.txt
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--> du -sh /home2
8.0K /home2
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--> df -h /home2
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 20G 18G 1015M 95% /
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--> tar --help
Usage: tar [OPTION...] [FILE]...
GNU `tar' saves many files together into a single tape or disk archive, and can
restore individual files from the archive.
Examples:
tar -cf archive.tar foo bar # Create archive.tar from files foo and bar.
tar -tvf archive.tar # List all files in archive.tar verbosely.
tar -xf archive.tar # Extract all files from archive.tar.
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 (not on mag tapes!)
-r, --append append files to the end of an archive
-t, --list list the contents of an archive
--test-label test the archive volume label and exit
-u, --update only append files newer than copy in archive
-x, --extract, --get extract files from an archive
Operation modifiers:
--check-device check device numbers when creating incremental
archives (default)
-g, --listed-incremental=FILE handle new GNU-format incremental backup
-G, --incremental handle old GNU-format incremental backup
--ignore-failed-read do not exit with nonzero on unreadable files
--level=NUMBER dump level for created listed-incremental archive
-n, --seek archive is seekable
--no-check-device do not check device numbers when creating
incremental archives
--no-seek archive is not seekable
--occurrence[=NUMBER] process only the NUMBERth occurrence of each file
in the archive; this option is valid only in
conjunction with one of the subcommands --delete,
--diff, --extract or --list and when a list of
files is given either on the command line or via
the -T option; NUMBER defaults to 1
--sparse-version=MAJOR[.MINOR]
set version of the sparse format to use (implies
--sparse)
-S, --sparse handle sparse files efficiently
Overwrite control:
-k, --keep-old-files don't replace existing files when extracting
--keep-newer-files don't replace existing files that are newer than
their archive copies
--no-overwrite-dir preserve metadata of existing directories
--overwrite overwrite existing files when extracting
--overwrite-dir overwrite metadata of existing directories when
extracting (default)
--recursive-unlink empty hierarchies prior to extracting directory
--remove-files remove files after adding them to the archive
-U, --unlink-first remove each file prior to extracting over it
-W, --verify attempt to verify the archive after writing it
Select output stream:
--ignore-command-error ignore exit codes of children
--no-ignore-command-error treat non-zero exit codes of children as
error
-O, --to-stdout extract files to standard output
--to-command=COMMAND pipe extracted files to another program
Handling of file attributes:
--atime-preserve[=METHOD] preserve access times on dumped files, either
by restoring the times after reading
(METHOD='replace'; default) or by not setting the
times in the first place (METHOD='system')
--delay-directory-restore delay setting modification times and
permissions of extracted directories until the end
of extraction
--group=NAME force NAME as group for added files
--mode=CHANGES force (symbolic) mode CHANGES for added files
--mtime=DATE-OR-FILE set mtime for added files from DATE-OR-FILE
-m, --touch don't extract file modified time
--no-delay-directory-restore
cancel the effect of --delay-directory-restore
option
--no-same-owner extract files as yourself (default for ordinary
users)
--no-same-permissions apply the user's umask when extracting permissions
from the archive (default for ordinary users)
--numeric-owner always use numbers for user/group names
--owner=NAME force NAME as owner for added files
-p, --preserve-permissions, --same-permissions
extract information about file permissions
(default for superuser)
--preserve same as both -p and -s
--same-owner try extracting files with the same ownership as
exists in the archive (default for superuser)
-s, --preserve-order, --same-order
sort names to extract to match archive
Device selection and switching:
-f, --file=ARCHIVE use archive file or device ARCHIVE
--force-local archive file is local even if it has a colon
-F, --info-script=NAME, --new-volume-script=NAME
run script at end of each tape (implies -M)
-L, --tape-length=NUMBER change tape after writing NUMBER x 1024 bytes
-M, --multi-volume create/list/extract multi-volume archive
--rmt-command=COMMAND use given rmt COMMAND instead of rmt
--rsh-command=COMMAND use remote COMMAND instead of rsh
--volno-file=FILE use/update the volume number in FILE
Device blocking:
-b, --blocking-factor=BLOCKS BLOCKS x 512 bytes per record
-B, --read-full-records reblock as we read (for 4.2BSD pipes)
-i, --ignore-zeros ignore zeroed blocks in archive (means EOF)
--record-size=NUMBER NUMBER of bytes per record, multiple of 512
Archive format selection:
-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
--old-archive, --portability
same as --format=v7
--pax-option=keyword[[:]=value][,keyword[[:]=value]]...
control pax keywords
--posix same as --format=posix
-V, --label=TEXT create archive with volume name TEXT; at
list/extract time, use TEXT as a globbing pattern
for volume name
Compression options:
-a, --auto-compress use archive suffix to determine the compression
program
-I, --use-compress-program=PROG
filter through PROG (must accept -d)
-j, --bzip2 filter the archive through bzip2
-J, --xz filter the archive through xz
--lzip filter the archive through lzip
--lzma filter the archive through lzma
--lzop
--no-auto-compress do not use archive suffix to determine the
compression program
-z, --gzip, --gunzip, --ungzip filter the archive through gzip
-Z, --compress, --uncompress filter the archive through compress
Local file selection:
--add-file=FILE add given FILE to the archive (useful if its name
starts with a dash)
--backup[=CONTROL] backup before removal, choose version CONTROL
-C, --directory=DIR change to directory DIR
--exclude=PATTERN exclude files, given as a PATTERN
--exclude-backups exclude backup and lock files
--exclude-caches exclude contents of directories containing
CACHEDIR.TAG, except for the tag file itself
--exclude-caches-all exclude directories containing CACHEDIR.TAG
--exclude-caches-under exclude everything under directories containing
CACHEDIR.TAG
--exclude-tag=FILE exclude contents of directories containing FILE,
except for FILE itself
--exclude-tag-all=FILE exclude directories containing FILE
--exclude-tag-under=FILE exclude everything under directories
containing FILE
--exclude-vcs exclude version control system directories
-h, --dereference follow symlinks; archive and dump the files they
point to
--hard-dereference follow hard links; archive and dump the files they
refer to
-K, --starting-file=MEMBER-NAME
begin at member MEMBER-NAME in the archive
--newer-mtime=DATE compare date and time when data changed only
--no-null disable the effect of the previous --null option
--no-recursion avoid descending automatically in directories
--no-unquote do not unquote filenames read with -T
--null -T reads null-terminated names, disable -C
-N, --newer=DATE-OR-FILE, --after-date=DATE-OR-FILE
only store files newer than DATE-OR-FILE
--one-file-system stay in local file system when creating archive
-P, --absolute-names don't strip leading `/'s from file names
--recursion recurse into directories (default)
--suffix=STRING backup before removal, override usual suffix ('~'
unless overridden by environment variable
SIMPLE_BACKUP_SUFFIX)
-T, --files-from=FILE get names to extract or create from FILE
--unquote unquote filenames read with -T (default)
-X, --exclude-from=FILE exclude patterns listed in FILE
File name transformations:
--strip-components=NUMBER strip NUMBER leading components from file
names on extraction
--transform=EXPRESSION, --xform=EXPRESSION
use sed replace EXPRESSION to transform file
names
File name matching options (affect both exclude and include patterns):
--anchored patterns match file name start
--ignore-case ignore case
--no-anchored patterns match after any `/' (default for
exclusion)
--no-ignore-case case sensitive matching (default)
--no-wildcards verbatim string matching
--no-wildcards-match-slash wildcards do not match `/'
--wildcards use wildcards (default for exclusion)
--wildcards-match-slash wildcards match `/' (default for exclusion)
Informative output:
--checkpoint[=NUMBER] display progress messages every NUMBERth record
(default 10)
--checkpoint-action=ACTION execute ACTION on each checkpoint
--full-time print file time to its full resolution
--index-file=FILE send verbose output to FILE
-l, --check-links print a message if not all links are dumped
--no-quote-chars=STRING disable quoting for characters from STRING
--quote-chars=STRING additionally quote characters from STRING
--quoting-style=STYLE set name quoting style; see below for valid STYLE
values
-R, --block-number show block number within archive with each
message
--show-defaults show tar defaults
--show-omitted-dirs when listing or extracting, list each directory
that does not match search criteria
--show-transformed-names, --show-stored-names
show file or archive names after transformation
--totals[=SIGNAL] print total bytes after processing the archive;
with an argument - print total bytes when this
SIGNAL is delivered; Allowed signals are: SIGHUP,
SIGQUIT, SIGINT, SIGUSR1 and SIGUSR2; the names
without SIG prefix are also accepted
--utc print file modification times in UTC
-v, --verbose verbosely list files processed
--warning=KEYWORD warning control
-w, --interactive, --confirmation
ask for confirmation for every action
Compatibility options:
-o when creating, same as --old-archive; when
extracting, same as --no-same-owner
Other options:
-?, --help give this help list
--restrict disable use of some potentially harmful options
--usage give a short usage message
--version print program version
Mandatory or optional arguments to long options are also mandatory or optional
for any corresponding short options.
The backup suffix is `~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX.
The version control may be set with --backup or VERSION_CONTROL, values are:
none, off never make backups
t, numbered make numbered backups
nil, existing numbered if numbered backups exist, simple otherwise
never, simple always make simple backups
Valid arguments for the --quoting-style option are:
literal
shell
shell-always
c
c-maybe
escape
locale
clocale
*This* tar defaults to:
--format=posix -f- -b20 --quoting-style=escape --rmt-command=/usr/lib/rmt
--rsh-command=/usr/bin/rsh
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--> sudo tar cvfz home2.tar /home2
tar: Removing leading `/' from member names
/home2/
/home2/test/
/home2/test/this-is-a-file.txt
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--> ll
total 32
-rw-r--r-- 1 luser users 4205 Jan 28 09:49 grep.help.txt
-rw-r--r-- 1 root root 346 Jan 28 10:06 home2.tar
-rw-r--r-- 1 luser users 20480 Jan 28 10:06 how-to-preserve-home.RAW
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--> file home2.tar
home2.tar: gzip compressed data, from Unix, last modified: Wed Jan 28 10:06:50 2015
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--> uncompress home2.tar
gzip: home2.tar: unknown suffix -- ignored
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--> gunzip home2.tar
Archive: home2.tar
End-of-central-directory signature not found. Either this file is not
a zipfile, or it constitutes one disk of a multi-part archive. In the
latter case the central directory and zipfile comment will be found on
the last disk(s) of this archive.
unzip: cannot find zipfile directory in one of home2.tar or
home2.tar.zip, and cannot find home2.tar.ZIP, period.
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--> tar xvfz home2.tar
home2/
home2/test/
home2/test/this-is-a-file.txt
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--> ll
total 36
-rw-r--r-- 1 luser users 4205 Jan 28 09:49 grep.help.txt
drwxr-xr-x 3 luser users 4096 Jan 28 10:04 home2
-rw-r--r-- 1 root root 346 Jan 28 10:06 home2.tar
-rw-r--r-- 1 luser users 20480 Jan 28 10:06 how-to-preserve-home.RAW
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--> ll home2
total 4
drwxr-xr-x 2 luser users 4096 Jan 28 10:05 test
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--> ll home2/test
total 0
-rw-r--r-- 1 luser users 0 Jan 28 10:05 this-is-a-file.txt
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--> ll
total 36
-rw-r--r-- 1 luser users 4205 Jan 28 09:49 grep.help.txt
drwxr-xr-x 3 luser users 4096 Jan 28 10:04 home2
-rw-r--r-- 1 root root 346 Jan 28 10:06 home2.tar
-rw-r--r-- 1 luser users 20480 Jan 28 10:06 how-to-preserve-home.RAW
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--> exit
exit
Script done on Wed 28 Jan 2015 10:08:08 AM PST
--> cat how-to-preserve-home.RAW | col -b > how-to-preserve-home.txt
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--> rm -f how-to-preserve-home.RAW ; vi how-to-preserve-home.txt
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