Here is a summary of archive and compression tools available on the Debian system.

Here is a summary of simple copy and backup tools available on the Debian system.

Here are several ways to archive and unarchive the entire content of the directory "/source" using different tools.

GNU tar(1):

$ tar cvzf archive.tar.gz /source
$ tar xvzf archive.tar.gz

cpio(1):

$ find /source -xdev -print0 | cpio -ov --null > archive.cpio; gzip archive.cpio
$ zcat archive.cpio.gz | cpio -i

afio(1):

$ find /source -xdev -print0 | afio -ovZ0 archive.afio
$ afio -ivZ archive.afio

Here are several ways to make the entire content of local or remote copies using different tools.

GNU cp(1) and openSSH scp(1):

# cp -a /source /dest
# scp -pr /source user@host.dom:/dest

GNU tar(1):

# (cd /source && tar cf - . ) | (cd /dest && tar xvfp - )
# (cd /source && tar cf - . ) | ssh user@host.dom '(cd /dest && tar xvfp - )'

cpio(1):

# cd /source; find . -print0 | cpio -pvdm --null --sparse /dest

afio(1):

# cd /source; find . -print0 | afio -pv0a /dest

# scp -pr user1@host1.dom:/source user2@host2.dom:/dest

find(1) is used to select files for archive and copy commands (see Section 10.1.3, “Idioms for the archive” and Section 10.1.4, “Idioms for the copy”) or for xargs(1) (see Section 9.5.9, “Repeating a command looping over files”). This can be enhanced by using its command arguments.

Basic syntax of find(1) can be summarized as the following.

find(1) is often used with an idiomatic style as the following.

# find /path/to \
    -xdev -regextype posix-extended \
    -type f -regex ".*\.afio|.*~" -prune -o \
    -type d -regex ".*/\.git" -prune -o \
    -type f -size +99M -prune -o \
    -type f -newer /path/to/timestamp -print0

This means to do following actions.

Please note the idiomatic use of "-prune -o" to exclude files in the above example.

We all know that computers fail sometime or human errors cause system and data damages. Backup and recovery operations are the essential part of successful system administration. All possible failure modes hit you some day.

There are 3 key factors which determine actual backup and recovery policy.

As for secure storage of data, data should be at least on different disk partitions preferably on different disks and machines to withstand the filesystem corruption. Important data are best stored on a write-once media such as CD/DVD-R to prevent overwrite accidents. (See Section 10.2, “The binary data” for how to write to the storage media from the shell commandline. GNOME desktop GUI environment gives you easy access via menu: "Places→CD/DVD Creator".)

Here is a select list of notable backup utility suites available on the Debian system.

Backup tools have their specialized focuses.

Basic tools described in Section 10.1.1, “Archive and compression tools” and Section 10.1.2, “Copy and synchronization tools” can be used to facilitate system backup via custom scripts. Such script can be enhanced by the following.

For a personal Debian desktop system running unstable suite, I only need to protect personal and critical data. I reinstall system once a year anyway. Thus I see no reason to backup the whole system or to install a full featured backup utility.

I use a simple script to make a backup archive and burn it into CD/DVD using GUI. Here is an example script for this.

#!/bin/sh -e
# Copyright (C) 2007-2008 Osamu Aoki <osamu@debian.org>, Public Domain
BUUID=1000; USER=osamu # UID and name of a user who accesses backup files
BUDIR="/var/backups"
XDIR0=".+/Mail|.+/Desktop"
XDIR1=".+/\.thumbnails|.+/\.?Trash|.+/\.?[cC]ache|.+/\.gvfs|.+/sessions"
XDIR2=".+/CVS|.+/\.git|.+/\.svn|.+/Downloads|.+/Archive|.+/Checkout|.+/tmp"
XSFX=".+\.iso|.+\.tgz|.+\.tar\.gz|.+\.tar\.bz2|.+\.afio|.+\.tmp|.+\.swp|.+~"
SIZE="+99M"
DATE=$(date --utc +"%Y%m%d-%H%M")
[ -d "$BUDIR" ] || mkdir -p "BUDIR"
umask 077
dpkg --get-selections \* > /var/lib/dpkg/dpkg-selections.list
debconf-get-selections > /var/cache/debconf/debconf-selections

{
find /etc /usr/local /opt /var/lib/dpkg/dpkg-selections.list \
     /var/cache/debconf/debconf-selections -xdev -print0
find /home/$USER /root -xdev -regextype posix-extended \
  -type d -regex "$XDIR0|$XDIR1" -prune -o -type f -regex "$XSFX" -prune -o \
  -type f -size  "$SIZE" -prune -o -print0
find /home/$USER/Mail/Inbox /home/$USER/Mail/Outbox -print0
find /home/$USER/Desktop  -xdev -regextype posix-extended \
  -type d -regex "$XDIR2" -prune -o -type f -regex "$XSFX" -prune -o \
  -type f -size  "$SIZE" -prune -o -print0
} | cpio -ov --null -O $BUDIR/BU$DATE.cpio
chown $BUUID $BUDIR/BU$DATE.cpio
touch $BUDIR/backup.stamp

This is meant to be a script example executed from root.

I expect you to change and execute this as follows.

Keep it simple!

For the set of data under a directory tree, the copy with "cp -a" provides the normal backup.

For the set of large non-overwritten static data under a directory tree such as the one under the "/var/cache/apt/packages/" directory, hardlinks with "cp -al" provide an alternative to the normal backup with efficient use of the disk space.

Here is a copy script, which I named as bkup, for the data backup. This script copies all (non-VCS) files under the current directory to the dated directory on the parent directory or on a remote host.

#!/bin/sh -e
# Copyright (C) 2007-2008 Osamu Aoki <osamu@debian.org>, Public Domain
function fdot(){ find . -type d \( -iname ".?*" -o -iname "CVS" \) -prune -o -print0;}
function fall(){ find . -print0;}
function mkdircd(){ mkdir -p "$1";chmod 700 "$1";cd "$1">/dev/null;}
FIND="fdot";OPT="-a";MODE="CPIOP";HOST="localhost";EXTP="$(hostname -f)"
BKUP="$(basename $(pwd)).bkup";TIME="$(date  +%Y%m%d-%H%M%S)";BU="$BKUP/$TIME"
while getopts gcCsStrlLaAxe:h:T f; do case $f in
g)  MODE="GNUCP";; # cp (GNU)
c)  MODE="CPIOP";; # cpio -p
C)  MODE="CPIOI";; # cpio -i
s)  MODE="CPIOSSH";; # cpio/ssh
S)  MODE="AFIOSSH";; # afio/ssh
t)  MODE="TARSSH";; # tar/ssh
r)  MODE="RSYNCSSH";; # rsync/ssh
l)  OPT="-alv";; # hardlink (GNU cp)
L)  OPT="-av";;  # copy (GNU cp)
a)  FIND="fall";; # find all
A)  FIND="fdot";; # find non CVS/ .???/
x)  set -x;; # trace
e)  EXTP="${OPTARG}";; # hostname -f
h)  HOST="${OPTARG}";; # user@remotehost.example.com
T)  MODE="TEST";; # test find mode
\?) echo "use -x for trace."
esac; done
shift $(expr $OPTIND - 1)
if [ $# -gt 0 ]; then
  for x in $@; do cp $OPT $x $x.$TIME; done
elif [ $MODE = GNUCP ]; then
  mkdir -p "../$BU";chmod 700 "../$BU";cp $OPT . "../$BU/"
elif [ $MODE = CPIOP ]; then
  mkdir -p "../$BU";chmod 700 "../$BU"
  $FIND|cpio --null --sparse -pvd ../$BU
elif [ $MODE = CPIOI ]; then
  $FIND|cpio -ov --null | ( mkdircd "../$BU"&&cpio -i )
elif [ $MODE = CPIOSSH ]; then
  $FIND|cpio -ov --null|ssh -C $HOST "( mkdircd \"$EXTP/$BU\"&&cpio -i )"
elif [ $MODE = AFIOSSH ]; then
  $FIND|afio -ov -0 -|ssh -C $HOST "( mkdircd \"$EXTP/$BU\"&&afio -i - )"
elif [ $MODE = TARSSH ]; then
  (tar cvf - . )|ssh -C $HOST "( mkdircd \"$EXTP/$BU\"&& tar xvfp - )"
elif [ $MODE = RSYNCSSH ]; then
  rsync -rlpt ./ "${HOST}:${EXTP}-${BKUP}-${TIME}"
else
  echo "Any other idea to backup?"
  $FIND |xargs -0 -n 1 echo
fi

This is meant to be command examples. Please read script and edit it by yourself before using it.

Removable storage devices may be any one of the following.

These removable storage devices can be automatically mounted as a user under modern desktop environment, such as GNOME using gnome-mount(1).

When sharing data with other system via removable storage device, you should format it with common filesystem supported by both systems. Here is a list of filesystem choices.

The FAT filesystem is supported by almost all modern operating systems and is quite useful for the data exchange purpose via removable hard disk like media.

When formatting removable hard disk like devices for cross platform sharing of data with the FAT filesystem, the following should be safe choices.

When using the FAT or ISO9660 filesystems for sharing data, the following should be the safe considerations.

When sharing data with other system via network, you should use common service. Here are some hints.

Although these filesystems mounted over network and file transfer methods over network are quite convenient for sharing data, these may be insecure. Their network connection must be secured by the following.

See also Section 6.10, “Other network application servers” and Section 6.11, “Other network application clients”.

When choosing computer data storage media for important data archive, you should be careful about their limitations. For small personal data backup, I use CD-R and DVD-R by the brand name company and store in a cool, shaded, dry, clean environment. (Tape archive media seem to be popular for professional use.)

Optimistic storage life of archive media seen on the net (mostly from vendor info).

These do not count on the mechanical failures due to handling etc.

Optimistic write cycle of archive media seen on the net (mostly from vendor info).

The disk image file, "disk.img", of an unmounted device, e.g., the second SCSI drive "/dev/sdb", can be made using cp(1) or dd(1) by the following.

# cp /dev/sdb disk.img
# dd if=/dev/sdb of=disk.img

The disk image of the traditional PC's master boot record (MBR) (see Section 9.3.1, “Disk partition configuration”) which reside on the first sector on the primary IDE disk can be made by using dd(1) by the following.

# dd if=/dev/hda of=mbr.img bs=512 count=1
# dd if=/dev/hda of=mbr-nopart.img bs=446 count=1
# dd if=/dev/hda of=mbr-part.img skip=446 bs=1 count=66

If you have a SCSI device (including the new serial ATA drive) as the boot disk, substitute "/dev/hda" with "/dev/sda".

If you are making an image of a disk partition of the original disk, substitute "/dev/hda" with "/dev/hda1" etc.

The disk image file, "disk.img" can be written to an unmounted device, e.g., the second SCSI drive "/dev/sdb" with matching size, by the following.

# dd if=disk.img of=/dev/sdb

Similarly, the disk partition image file, "disk.img" can be written to an unmounted partition, e.g., the first partition of the second SCSI drive "/dev/sdb1" with matching size, by the following.

# dd if=disk.img of=/dev/sdb1

If "disk.img" contains an image of the disk contents and the original disk had a disk configuration which gives xxxx = (bytes/sector) * (sectors/cylinder), then the following mounts it to "/mnt".

# mount -o loop,offset=xxxx disk.img /mnt

This offset is to skip MBR of the hard disk. You can skip this offset in the above example, if "disk.img" contains only the following.

An empty disk image file, "sparse", which can grow up to 5MiB can be made using dd(1) and mke2fs(8) by the following.

$ dd bs=1 count=0 if=/dev/zero of=sparse seek=5G
$ /sbin/mke2fs sparse
mke2fs 1.41.3 (12-Oct-2008)
sparse is not a block special device.
Proceed anyway? (y,n) y
...
$ du  --apparent-size -h sparse
5.0G  sparse
$ du -h sparse
83M sparse

For "sparse", its file size is 5.0 GiB and its actual disk usage is mere 83MiB. This discrepancy is possible since ext2fs can hold sparse file.

The most basic viewing method of binary data is to use "od -t x1" command.

There are tools to read and write files without mounting disk.

Software RAID systems offered by the Linux kernel provide data redundancy in the kernel filesystem level to achieve high levels of storage reliability.

There are tools to add data redundancy to files in application program level to achieve high levels of storage reliability, too.

There are tools for data file recovery and forensic analysis.

The ISO9660 image file, "cd.iso", from the source directory tree at "source_directory" can be made using genisoimage(1) provided by cdrkit by the following.

#  genisoimage -r -J -T -V volume_id -o cd.iso source_directory

Similary, the bootable ISO9660 image file, "cdboot.iso", can be made from debian-installer like directory tree at "source_directory" by the following.

#  genisoimage -r -o cdboot.iso -V volume_id \
   -b isolinux/isolinux.bin -c isolinux/boot.cat \
   -no-emul-boot -boot-load-size 4 -boot-info-table source_directory

Here Isolinux boot loader (see Section 3.3, “Stage 2: the boot loader”) is used for booting.

To make the disk image directly from the CD-ROM device using cp(1) or dd(1) has a few problems. The first run of dd(1) may cause an error message and may yield a shorter disk image with a lost tail-end. The second run of dd(1) may yield a larger disk image with garbage data attached at the end on some systems if the data size is not specified. Only the second run of dd(1) with the correct data size specified, and without ejecting the CD after an error message, seems to avoid these problems. If for example the image size displayed by df(1) is 46301184 blocks, use the following command twice to get the right image (this is my empirical information).

# dd if=/dev/cdrom of=cd.iso bs=2048 count=$((46301184/2))

You can find a usable device by the following.

# wodim --devices

Then the blank CD-R is inserted to the CD drive, and the ISO9660 image file, "cd.iso" is written to this device, e.g., "/dev/hda", using wodim(1) by the following.

# wodim -v -eject dev=/dev/hda cd.iso

If CD-RW is used instead of CD-R, do this instead by the following.

# wodim -v -eject blank=fast dev=/dev/hda cd.iso

If "cd.iso" contains an ISO9660 image, then the following manually mounts it to "/cdrom" by the following.

# mount -t iso9660 -o ro,loop cd.iso /cdrom

When a data is too big to backup as a single file, you can backup its content after splitting it into, e.g. 2000MiB chunks and merge those chunks back into the original file later.

$ split -b 2000m large_file
$ cat x* >large_file

In order to clear the contents of a file such as a log file, do not use rm(1) to delete the file and then create a new empty file, because the file may still be accessed in the interval between commands. The following is the safe way to clear the contents of the file.

$ :>file_to_be_cleared

The following commands create dummy or empty files.

$ dd if=/dev/zero    of=5kb.file bs=1k count=5
$ dd if=/dev/urandom of=7mb.file bs=1M count=7
$ touch zero.file
$ : > alwayszero.file

You should find following files.

There are several ways to completely erase data from an entire hard disk like device, e.g., USB memory stick at "/dev/sda".

Erase all the disk content by resetting data to 0 with the following.

# dd if=/dev/zero of=/dev/sda

Erase all by overwriting random data with the following.

# dd if=/dev/urandom of=/dev/sda

Erase all by overwriting random data very efficiently with the following.

# shred -v -n 1 /dev/sda

Since dd(1) is available from the shell of many bootable Linux CDs such as Debian installer CD, you can erase your installed system completely by running an erase command from such media on the system hard disk, e.g., "/dev/hda", "/dev/sda", etc.

Even if you have accidentally deleted a file, as long as that file is still being used by some application (read or write mode), it is possible to recover such a file.

For example, try the following

$ echo foo > bar
$ less bar
$ ps aux | grep ' less[ ]'
bozo    4775  0.0  0.0  92200   884 pts/8    S+   00:18   0:00 less bar
$ rm bar
$ ls -l /proc/4775/fd | grep bar
lr-x------ 1 bozo bozo 64 2008-05-09 00:19 4 -> /home/bozo/bar (deleted)
$ cat /proc/4775/fd/4 >bar
$ ls -l
-rw-r--r-- 1 bozo bozo 4 2008-05-09 00:25 bar
$ cat bar
foo

Execute on another terminal (when you have the lsof package installed) as follows.

$ ls -li bar
2228329 -rw-r--r-- 1 bozo bozo 4 2008-05-11 11:02 bar
$ lsof |grep bar|grep less
less 4775 bozo 4r REG 8,3 4 2228329 /home/bozo/bar
$ rm bar
$ lsof |grep bar|grep less
less 4775 bozo 4r REG 8,3 4 2228329 /home/bozo/bar (deleted)
$ cat /proc/4775/fd/4 >bar
$ ls -li bar
2228302 -rw-r--r-- 1 bozo bozo 4 2008-05-11 11:05 bar
$ cat bar
foo

Files with hardlinks can be identified by "ls -li".

$ ls -li
total 0
2738405 -rw-r--r-- 1 root root 0 2008-09-15 20:21 bar
2738404 -rw-r--r-- 2 root root 0 2008-09-15 20:21 baz
2738404 -rw-r--r-- 2 root root 0 2008-09-15 20:21 foo

Both "baz" and "foo" have link counts of "2" (>1) showing them to have hardlinks. Their inode numbers are common "2738404". This means they are the same hardlinked file. If you do not happen to find all hardlinked files by chance, you can search it by the inode, e.g., "2738404" as the following.

# find /path/to/mount/point -xdev -inum 2738404

All deleted but open files consumes disk space although they are not visible from normal du(1). They can be listed with their size by the following.

# lsof -s -X / |grep deleted

Here are GNU Privacy Guard commands for the basic key management.

Here is the meaning of the trust code.

The following uploads my key "A8061F32" to the popular keyserver "hkp://subkeys.pgp.net".

$ gpg --keyserver hkp://subkeys.pgp.net --send-keys A8061F32

A good default keyserver set up in "~/.gnupg/gpg.conf" (or old location "~/.gnupg/options") contains the following.

keyserver hkp://subkeys.pgp.net

The following obtains unknown keys from the keyserver.

$ gpg --list-sigs | \
  sed -n '/^sig.*\[User ID not found\]/s/^sig..........\(\w\w*\)\W.*/\1/p' |\
  sort | uniq | xargs gpg --recv-keys

There was a bug in OpenPGP Public Key Server (pre version 0.9.6) which corrupted key with more than 2 sub-keys. The newer gnupg (>1.2.1-2) package can handle these corrupted subkeys. See gpg(1) under "--repair-pks-subkey-bug" option.

Here are examples for using GNU Privacy Guard commands on files.

Add the following to "~/.muttrc" to keep a slow GnuPG from automatically starting, while allowing it to be used by typing "S" at the index menu.

macro index S ":toggle pgp_verify_sig\n"
set pgp_verify_sig=no

The gnupg plugin let you run GnuPG transparently for files with extension ".gpg", ".asc", and ".ppg".

# aptitude install vim-scripts vim-addon-manager
$ vim-addons install gnupg

md5sum(1) provides utility to make a digest file using the method in rfc1321 and verifying each file with it.

$ md5sum foo bar >baz.md5
$ cat baz.md5
d3b07384d113edec49eaa6238ad5ff00  foo
c157a79031e1c40f85931829bc5fc552  bar
$ md5sum -c baz.md5
foo: OK
bar: OK

One of following procedures extract differences between two source files and create unified diff files "file.patch0" or "file.patch1" depending on the file location.

$ diff -u file.old file.new > file.patch0
$ diff -u old/file new/file > file.patch1

The diff file (alternatively called patch file) is used to send a program update. The receiving party applies this update to another file by the following.

$ patch -p0 file < file.patch0
$ patch -p1 file < file.patch1

If you have three versions of a source code, you can perform 3-way-merge effectively using diff3(1) by the following.

$ diff3 -m file.mine file.old file.yours > file

Here is an oversimplified comparison of native VCS commands to provide the big picture. The typical command sequence may require options and arguments.

The following configuration allows commits to the CVS repository only by a member of the "src" group, and administration of CVS only by a member of the "staff" group, thus reducing the chance of shooting oneself.

# cd /var/lib; umask 002; mkdir cvs
# export CVSROOT=/srv/cvs/project
# cd $CVSROOT
# chown root:src .
# chmod 2775 .
# cvs -d $CVSROOT init
# cd CVSROOT
# chown -R root:staff .
# chmod 2775 .
# touch val-tags
# chmod 664 history val-tags
# chown root:src history val-tags

The default CVS repository is pointed by "$CVSROOT". The following sets up "$CVSROOT" for the local access.

$ export CVSROOT=/srv/cvs/project

Many public CVS servers provide read-only remote access to them with account name "anonymous" via pserver service. For example, Debian web site contents are maintained by webwml project via CVS at Debian alioth service. The following sets up "$CVSROOT" for the remote access to this CVS repository.

$ export CVSROOT=:pserver:anonymous@cvs.alioth.debian.org:/cvsroot/webwml
$ cvs login

The following sets up "$CVS_RSH" and "$CVSROOT" for the remote access to the CVS repository by webwml project with SSH.

$ export CVS_RSH=ssh
$ export CVSROOT=:ext:account@cvs.alioth.debian.org:/cvs/webwml

You can also use public key authentication for SSH which eliminates the remote password prompt.

Create a new local source tree location at "~/path/to/module1" by the following.

$ mkdir -p ~/path/to/module1; cd ~/path/to/module1

Populate a new local source tree under "~/path/to/module1" with files.

Import it to CVS with the following parameters.

$ cd ~/path/to/module1
$ cvs import -m "Start module1" module1 Main-branch Release-initial
$ rm -Rf . # optional

CVS does not overwrite the current repository file but replaces it with another one. Thus, write permission to the repository directory is critical. For every new module for "module1" in repository at "/srv/cvs/project", run the following to ensure this condition if needed.

# cd /srv/cvs/project
# chown -R root:src module1
# chmod -R ug+rwX   module1
# chmod    2775     module1

Here is an example of typical work flow using CVS.

Check all available modules from CVS project pointed by "$CVSROOT" by the following.

$ cvs rls
CVSROOT
module1
module2
...

Checkout "module1" to its default directory "./module1" by the following.

$ cd ~/path/to
$ cvs co module1
$ cd module1

Make changes to the content as needed.

Check changes by making "diff -u [repository] [local]" equivalent by the following.

$ cvs diff -u

You find that you broke some file "file_to_undo" severely but other files are fine.

Overwrite "file_to_undo" file with the clean copy from CVS by the following.

$ cvs up -C file_to_undo

Save the updated local source tree to CVS by the following.

$ cvs ci -m "Describe change"

Create and add "file_to_add" file to CVS by the following.

$ vi file_to_add
$ cvs add file_to_add
$ cvs ci -m "Added file_to_add"

Merge the latest version from CVS by the following.

$ cvs up -d

Watch out for lines starting with "C filename" which indicates conflicting changes.

Look for unmodified code in ".#filename.version".

Search for "<<<<<<<" and ">>>>>>>" in files for conflicting changes.

Edit files to fix conflicts as needed.

Add a release tag "Release-1" by the following.

$ cvs ci -m "last commit for Release-1"
$ cvs tag Release-1

Edit further.

Remove the release tag "Release-1" by the following.

$ cvs tag -d Release-1

Check in changes to CVS by the following.

$ cvs ci -m "real last commit for Release-1"

Re-add the release tag "Release-1" to updated CVS HEAD of main by the following.

$ cvs tag Release-1

Create a branch with a sticky branch tag "Release-initial-bugfixes" from the original version pointed by the tag "Release-initial" and check it out to "~/path/to/old" directory by the following.

$ cvs rtag -b -r Release-initial Release-initial-bugfixes module1
$ cd ~/path/to
$ cvs co -r Release-initial-bugfixes -d old module1
$ cd old

Work on this local source tree having the sticky tag "Release-initial-bugfixes" which is based on the original version.

Work on this branch by yourself … until someone else joins to this "Release-initial-bugfixes" branch.

Sync with files modified by others on this branch while creating new directories as needed by the following.

$ cvs up -d

Edit files to fix conflicts as needed.

Check in changes to CVS by the following.

$ cvs ci -m "checked into this branch"

Update the local tree by HEAD of main while removing sticky tag ("-A") and without keyword expansion ("-kk") by the following.

$ cvs up -d -kk -A

Update the local tree (content = HEAD of main) by merging from the "Release-initial-bugfixes" branch and without keyword expansion by the following.

$ cvs up -d -kk -j Release-initial-bugfixes

Fix conflicts with editor.

Check in changes to CVS by the following.

$ cvs ci -m "merged Release-initial-bugfixes"

Make archive by the following.

$ cd ..
$ mv old old-module1-bugfixes
$ tar -cvzf old-module1-bugfixes.tar.gz old-module1-bugfixes
$ rm -rf old-module1-bugfixes

To get the latest files from CVS, use "tomorrow" by the following.

$ cvs ex -D tomorrow module_name

Add module alias "mx" to a CVS project (local server) by the following.

$ export CVSROOT=/srv/cvs/project
$ cvs co CVSROOT/modules
$ cd CVSROOT
$ echo "mx -a module1" >>modules
$ cvs ci -m "Now mx is an alias for module1"
$ cvs release -d .

Now, you can check out "module1" (alias: "mx") from CVS to "new" directory by the following.

$ cvs co -d new mx
$ cd new

When you checkout files from CVS, their execution permission bit is retained.

Whenever you see execution permission problems in a checked out file, e.g. "filename", change its permission in the corresponding CVS repository by the following to fix it.

# chmod ugo-x filename

Currently, the subversion package does not set up a repository, so one must set it up manually. One possible location for a repository is in "/srv/svn/project".

Create a directory by the following.

# mkdir -p        /srv/svn/project

Create the repository database by the following.

# svnadmin create /srv/svn/project

If you only access Subversion repository via Apache2 server, you just need to make the repository only writable by the WWW server by the following.

# chown -R www-data:www-data /srv/svn/project

Add (or uncomment) the following in "/etc/apache2/mods-available/dav_svn.conf" to allow access to the repository via user authentication.

<Location /project>
  DAV svn
  SVNPath /srv/svn/project
  AuthType Basic
  AuthName "Subversion repository"
  AuthUserFile /etc/subversion/passwd
<LimitExcept GET PROPFIND OPTIONS REPORT>
    Require valid-user
</LimitExcept>
</Location>

Create a user authentication file with the command by the following.

# htpasswd2 -c /etc/subversion/passwd some-username

Restart Apache2.

Your new Subversion repository is accessible at URL "http://localhost/project" and "http://example.com/project" from svn(1) (assuming your URL of web server is "http://example.com/").

The following sets up Subversion repository for the local access by a group, e.g. project.

# chmod  2775     /srv/svn/project
# chown -R root:src /srv/svn/project
# chmod -R ug+rwX   /srv/svn/project

Your new Subversion repository is group accessible at URL "file:///localhost/srv/svn/project" or "file:///srv/svn/project" from svn(1) for local users belonging to project group. You must run commands, such as svn, svnserve, svnlook, and svnadmin under "umask 002" to ensure group access.

A group accessible Subversion repository is at URL "example.com:/srv/svn/project" for SSH, you can access it from svn(1) at URL "svn+ssh://example.com:/srv/svn/project".

Many projects uses directory tree similar to the following for Subversion to compensate its lack of branches and tags.

  ----- module1
    |   |-- branches
    |   |-- tags
    |   |   |-- release-1.0
    |   |   `-- release-2.0
    |   |
    |   `-- trunk
    |       |-- file1
    |       |-- file2
    |       `-- file3
    |
    `-- module2

Create a new local source tree location at "~/path/to/module1" by the following.

$ mkdir -p ~/path/to/module1; cd ~/path/to/module1

Populate a new local source tree under "~/path/to/module1" with files.

Import it to Subversion with the following parameters.

$ cd ~/path/to/module1
$ svn import file:///srv/svn/project/module1/trunk -m "Start module1"
$ svn cp file:///srv/svn/project/module1/trunk file:///srv/svn/project/module1/tags/Release-initial

Alternatively, by the following.

$ svn import ~/path/to/module1 file:///srv/svn/project/module1/trunk -m "Start module1"
$ svn cp file:///srv/svn/project/module1/trunk file:///srv/svn/project/module1/tags/Release-initial

Here is an example of typical work flow using Subversion.

Check all available modules from Subversion project pointed by URL "file:///srv/svn/project" by the following.

$ svn list file:///srv/svn/project
module1
module2
...

Checkout "module1/trunk" to a directory "module1" by the following.

$ cd ~/path/to
$ svn co file:///srv/svn/project/module1/trunk module1
$ cd module1

Make changes to the content as needed.

Check changes by making "diff -u [repository] [local]" equivalent by the following.

$ svn diff

You find that you broke some file "file_to_undo" severely but other files are fine.

Overwrite "file_to_undo" file with the clean copy from Subversion by the following.

$ svn revert file_to_undo

Save the updated local source tree to Subversion by the following.

$ svn ci -m "Describe change"

Create and add "file_to_add" file to Subversion by the following.

$ vi file_to_add
$ svn add file_to_add
$ svn ci -m "Added file_to_add"

Merge the latest version from Subversion by the following.

$ svn up

Watch out for lines starting with "C filename" which indicates conflicting changes.

Look for unmodified code in, e.g., "filename.r6", "filename.r9", and "filename.mine".

Search for "<<<<<<<" and ">>>>>>>" in files for conflicting changes.

Edit files to fix conflicts as needed.

Add a release tag "Release-1" by the following.

$ svn ci -m "last commit for Release-1"
$ svn cp file:///srv/svn/project/module1/trunk file:///srv/svn/project/module1/tags/Release-1

Edit further.

Remove the release tag "Release-1" by the following.

$ svn rm file:///srv/svn/project/module1/tags/Release-1

Check in changes to Subversion by the following.

$ svn ci -m "real last commit for Release-1"

Re-add the release tag "Release-1" from updated Subversion HEAD of trunk by the following.

$ svn cp file:///srv/svn/project/module1/trunk file:///srv/svn/project/module1/tags/Release-1

Create a branch with a path "module1/branches/Release-initial-bugfixes" from the original version pointed by the path "module1/tags/Release-initial" and check it out to "~/path/to/old" directory by the following.

$ svn cp file:///srv/svn/project/module1/tags/Release-initial file:///srv/svn/project/module1/branches/Release-initial-bugfixes
$ cd ~/path/to
$ svn co file:///srv/svn/project/module1/branches/Release-initial-bugfixes old
$ cd old

Work on this local source tree pointing to branch "Release-initial-bugfixes" which is based on the original version.

Work on this branch by yourself … until someone else joins to this "Release-initial-bugfixes" branch.

Sync with files modified by others on this branch by the following.

$ svn up

Edit files to fix conflicts as needed.

Check in changes to Subversion by the following.

$ svn ci -m "checked into this branch"

Update the local tree with HEAD of trunk by the following.

$ svn switch file:///srv/svn/project/module1/trunk

Update the local tree (content = HEAD of trunk) by merging from the "Release-initial-bugfixes" branch by the following.

$ svn merge file:///srv/svn/project/module1/branches/Release-initial-bugfixes

Fix conflicts with editor.

Check in changes to Subversion by the following.

$ svn ci -m "merged Release-initial-bugfixes"

Make archive by the following.

$ cd ..
$ mv old old-module1-bugfixes
$ tar -cvzf old-module1-bugfixes.tar.gz old-module1-bugfixes
$ rm -rf old-module1-bugfixes

You may wish to set several global configuration in "~/.gitconfig" such as your name and email address used by Git by the following.

$ git config --global user.name "Name Surname"
$ git config --global user.email yourname@example.com

If you are too used to CVS or Subversion commands, you may wish to set several command aliases by the following.

$ git config --global alias.ci "commit -a"
$ git config --global alias.co checkout

You can check your global configuration by the following.

$ git config --global --list

See the following.

git-gui(1) and gitk(1) commands make using Git very easy.

Even if your upstream uses different VCS, it may be good idea to use git(1) for local activity since you can manage your local copy of source tree without the network connection to the upstream. Here are some packages and commands used with git(1).

You can manually record chronological history of configuration using Git tools. Here is a simple example for your practice to record "/etc/apt/" contents.

$ cd /etc/apt/
$ sudo git init
$ sudo chmod 700 .git
$ sudo git add .
$ sudo git commit -a

Commit configuration with description.

Make modification to the configuration files.

$ cd /etc/apt/
$ sudo git commit -a

Commit configuration with description and continue your life.

$ cd /etc/apt/
$ sudo gitk --all

You have full configuration history with you.