Archiving with Tar

Tar files place several files or the contents of a directory or directories in one file. This is a good way to create backups and archives. Usually, tar files end with the .tar extension.

To create a tar file, type:

tar -cvf filename.tar files/directories

In this example, filename.tar represents the file you are creating and files/directories represents the files or directories you want to put in the new file.

tar -xvf foo.tar

This command does not remove the .tar file, but it places copies of the .tar contents in the current working directory.

The tar command does not compress files automatically. You can compress tar files with:

tar -czvf foo.tar

Compressed tar files are conventionally given the extension .tgz and are compressed with gzip.

To expand a compressed tar file type:

create:

extracting:

testing/viewing:

tar xvf **.tar.tar

$ du -hs /path/to/directory

Vi: Search and Replace

Change to normal mode with <ESC>.

Search (Wraped around at end of file):

  Search STRING forward :   / STRING.
  Search STRING backward:   ? STRING.

  Repeat search:   n
  Repeat search in opposite direction:  N  (SHIFT-n)

 
 First occurrence on current line:      :s/OLD/NEW
  
 Globally (all) on current line:        :s/OLD/NEW/g 

 Between two lines #,#:                 :#,#s/OLD/NEW/g
  
 Every occurrence in file:              :%s/OLD/NEW/g 

check all process of certain user :


$ top -u johndoe

$ top -u 500

$ top -U johndoe








kill all process of certain user:
kill -9 `ps -u <username> -o "pid="` 

sudo apt-get install linux-headers-$(uname -r)

Linux / Unix Command: ps / kill

Command Library

Even on Linux it sometimes happens that processes wear out their welcome and stick around longer than you would like them to. They simply ignore your request to close up and go away. Fortunately you have a powerful gun at your disposal that will clean out anything that doesn't get a hint: The Arnold Schwarzenegger equivalent among the Linux commands is the kill command.

The kill command works together with the ps command

• With the ps command (ps stands for "process status") you find out the identity of the program you want to get rid of.
• Then kill will finish it off.

  Here's how you do it:

The ps Command

It is used to display the currently running processes on Unix/Linux systems. If you know the 'Task-Manager" which pops up under Windows NT/2000/XP when you press CTRL+ALT+DEL then you will quickly grasp what ps does on Linux. It can show you the processes on your system in various formats. Here is a typical example:

To display all processes owned by the current user type ps ux and hit return:

$ ps ux

This will show a listing of processes similar to:

USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
jhaas 3064 0.1 3.6 18324 9088 ? S 17:55 0:00 /usr/bin/gnome-session
jhaas 3107 0.0 0.3 3128 968 ? S 17:55 0:00 /usr/bin/ssh-agent /etc/X11/xinit/Xclients
jhaas 3112 0.1 2.9 11208 7376 ? S 17:55 0:00 /usr/libexec/gconfd-2 11
jhaas 3130 0.0 0.6 3584 1696 ? S 17:55 0:00 xscreensaver -nosplash
jhaas 3133 0.8 5.3 21744 13216 ? S 17:55 0:03 gnome-panel --sm-client-id default2
jhaas 3137 0.0 2.4 16296 6172 ? S 17:55 0:00 magicdev --sm-client-id default4
jhaas 3141 0.0 2.8 16676 6936 ? S 17:55 0:00 eggcups --sm-client-id default6
jhaas 3143 0.0 1.7 11652 4308 ? S 17:55 0:00 pam-panel-icon --sm-client-id default0
jhaas 3145 0.2 5.4 24280 13564 ? S 17:55 0:01 /usr/bin/python /usr/bin/rhn-applet-gui --sm-client-id default5
jhaas 3154 0.3 4.1 23856 10172 ? S 17:55 0:01 evolution
jhaas 3157 0.0 0.9 5636 2228 ? S 17:55 0:00 oafd --ac-activate --ior-output-fd=10
jhaas 3216 0.2 3.1 12788 7844 ? S 17:56 0:00 emacs
jhaas 3218 1.3 4.0 20248 9904 ? R 17:56 0:04 gnome-terminal
jhaas 3219 0.0 0.2 1852 572 ? S 17:56 0:00 [gnome-pty-helpe]
jhaas 3220 0.0 0.5 4316 1388 pts/0 S 17:56 0:00 bash
jhaas 3268 0.0 0.2 2636 684 pts/0 R 18:01 0:00 ps ux

The kill Command

Now, if you want to terminate for example the emacs process you would look up the process identifier (PID) in the above table (3216), and say:

$ kill -9 3216

The -9 will ensure "execution".

A convenient short cut is the Alt-Ctrl-Esc key combination, which allows you to simply click on the application you want to kill.

df - Linux command line tool to display disk space usage

-h, --human-readable
print sizes in human readable format (e.g., 1K 234M 2G)

-H, --si
likewise, but use powers of 1000 not 1024

-i, --inodes
list inode information instead of block usage

-k like --block-size=1K

-l, --local
limit listing to local file systems

--no-sync
do not invoke sync before getting usage info (default)

-P, --portability
use the POSIX output format

--sync invoke sync before getting usage info

-t, --type=TYPE
limit listing to file systems of type TYPE

-T, --print-type
print file system type

-x, --exclude-type=TYPE
limit listing to file systems not of type TYPE

-v (ignored)

--help display this help and exit

--version
output version information and exit

Examples

If you use df with no options it will display all the available filesystems' info

$ df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 151225248 16280980 127262392 12% /
tmpfs 517924 0 517924 0% /lib/init/rw
udev 10240 60 10180 1% /dev
tmpfs 517924 0 517924 0% /dev/shm
/dev/sdb1 76896316 54820876 18169240 76% /media/discob
sshfs#ggarron@alketech.com:/home/ggarron/
7999999992 0 7999999992 0% /mnt/remote

To better understand what is in the screen can be used the -h (human readable)

$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 145G 16G 122G 12% /
tmpfs 506M 0 506M 0% /lib/init/rw
udev 10M 60K 10M 1% /dev
tmpfs 506M 0 506M 0% /dev/shm
/dev/sdb1 74G 53G 18G 76% /media/discob
sshfs#ggarron@alketech.com:/home/ggarron/
7.5T 0 7.5T 0% /mnt/remote

To display only local mounted systemfilesystems use the -l (local) options, you will see the sshfs remote filesystem is not shown anymore.

$ df -hl
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 145G 16G 122G 12% /
tmpfs 506M 0 506M 0% /lib/init/rw
udev 10M 60K 10M 1% /dev
tmpfs 506M 0 506M 0% /dev/shm
/dev/sdb1 74G 53G 18G 76% /media/discob

You can use it pointed to the device path or to the path where the filesystem is mounted

$ df -h /dev/sdb1
Filesystem Size Used Avail Use% Mounted on
/dev/sdb1 74G 53G 18G 76% /media/discob

$ df -h /media/discob/
Filesystem Size Used Avail Use% Mounted on
/dev/sdb1 74G 53G 18G 76% /media/discob

An A-Z Index of the Linux BASH command line

alias    Create an alias
apropos  Search Help manual pages (man -k)
awk      Find and Replace text, database sort/validate/index
break    Exit from a loop
builtin  Run a shell builtin
bzip2    Compress or decompress named file(s)

cal      Display a calendar
case     Conditionally perform a command
cat      Display the contents of a file
cd       Change Directory
cfdisk   Partition table manipulator for Linux
chgrp    Change group ownership
chmod    Change access permissions
chown    Change file owner and group
chroot   Run a command with a different root directory
cksum    Print CRC checksum and byte counts
clear    Clear terminal screen
cmp      Compare two files
comm     Compare two sorted files line by line
command  Run a command - ignoring shell functions
continue Resume the next iteration of a loop
cp       Copy one or more files to another location
cron     Daemon to execute scheduled commands
crontab  Schedule a command to run at a later time
csplit   Split a file into context-determined pieces
cut      Divide a file into several parts

date     Display or change the date & time
dc       Desk Calculator
dd       Data Dump - Convert and copy a file
declare  Declare variables and give them attributes
df       Display free disk space
diff     Display the differences between two files
diff3    Show differences among three files
dig      DNS lookup
dir      Briefly list directory contents
dircolors Colour setup for `ls'
dirname  Convert a full pathname to just a path
dirs     Display list of remembered directories
du       Estimate file space usage

echo     Display message on screen
egrep    Search file(s) for lines that match an extended expression
eject    Eject removable media
enable   Enable and disable builtin shell commands
env      Environment variables
ethtool  Ethernet card settings
eval     Evaluate several commands/arguments
exec     Execute a command
exit     Exit the shell
expand   Convert tabs to spaces
export   Set an environment variable
expr     Evaluate expressions

false    Do nothing, unsuccessfully
fdformat Low-level format a floppy disk
fdisk    Partition table manipulator for Linux
fgrep    Search file(s) for lines that match a fixed string
file     Determine file type
find     Search for files that meet a desired criteria
fmt      Reformat paragraph text
fold     Wrap text to fit a specified width.
for      Expand words, and execute commands
format   Format disks or tapes
free     Display memory usage
fsck     File system consistency check and repair
ftp      File Transfer Protocol
function Define Function Macros

gawk     Find and Replace text within file(s)
getopts  Parse positional parameters
grep     Search file(s) for lines that match a given pattern
groups   Print group names a user is in
gzip     Compress or decompress named file(s)

hash     Remember the full pathname of a name argument
head     Output the first part of file(s)
history  Command History
hostname Print or set system name

id       Print user and group id's
if       Conditionally perform a command
ifconfig Configure a network interface
import   Capture an X server screen and save the image to file
install  Copy files and set attributes

join     Join lines on a common field

kill     Stop a process from running

less     Display output one screen at a time
let      Perform arithmetic on shell variables
ln       Make links between files
local    Create variables
locate   Find files
logname  Print current login name
logout   Exit a login shell
look     Display lines beginning with a given string
lpc      Line printer control program
lpr      Off line print
lprint   Print a file
lprintd  Abort a print job
lprintq  List the print queue
lprm     Remove jobs from the print queue
ls       List information about file(s)
lsof     List open files

make     Recompile a group of programs
man      Help manual
mkdir    Create new folder(s)
mkfifo   Make FIFOs (named pipes)
mkisofs  Create an hybrid ISO9660/JOLIET/HFS filesystem
mknod    Make block or character special files
more     Display output one screen at a time
mount    Mount a file system
mtools   Manipulate MS-DOS files
mv       Move or rename files or directories

netstat  Networking information
nice     Set the priority of a command or job
nl       Number lines and write files
nohup    Run a command immune to hangups
nslookup Query Internet name servers interactively

passwd   Modify a user password
paste    Merge lines of files
pathchk  Check file name portability
ping     Test a network connection
popd     Restore the previous value of the current directory
pr       Prepare files for printing
printcap Printer capability database
printenv Print environment variables
printf   Format and print data
ps       Process status
pushd    Save and then change the current directory
pwd      Print Working Directory

quota    Display disk usage and limits
quotacheck Scan a file system for disk usage
quotactl Set disk quotas

ram      ram disk device
rcp      Copy files between two machines.
read     read a line from standard input
readonly Mark variables/functions as readonly
remsync  Synchronize remote files via email
return   Exit a shell function
rm       Remove files
rmdir    Remove folder(s)
rsync    Remote file copy (Synchronize file trees)

screen   Terminal window manager
scp      Secure copy (remote file copy)
sdiff    Merge two files interactively
sed      Stream Editor
select   Accept keyboard input
seq      Print numeric sequences
set      Manipulate shell variables and functions
sftp     Secure File Transfer Program
shift    Shift positional parameters
shopt    Shell Options
shutdown Shutdown or restart linux
sleep    Delay for a specified time
sort     Sort text files
source   Run commands from a file `.'
split    Split a file into fixed-size pieces
ssh      Secure Shell client (remote login program)
strace   Trace system calls and signals
su       Substitute user identity
sum      Print a checksum for a file
symlink  Make a new name for a file
sync     Synchronize data on disk with memory

tail     Output the last part of files
tar      Tape ARchiver
tee      Redirect output to multiple files
test     Evaluate a conditional expression
time     Measure Program running time
times    User and system times
touch    Change file timestamps
top      List processes running on the system
traceroute Trace Route to Host
trap     Run a command when a signal is set(bourne)
tr       Translate, squeeze, and/or delete characters
true     Do nothing, successfully
tsort    Topological sort
tty      Print filename of terminal on stdin
type     Describe a command

ulimit   Limit user resources
umask    Users file creation mask
umount   Unmount a device
unalias  Remove an alias
uname    Print system information
unexpand Convert spaces to tabs
uniq     Uniquify files
units    Convert units from one scale to another
unset    Remove variable or function names
unshar   Unpack shell archive scripts
until    Execute commands (until error)
useradd  Create new user account
usermod  Modify user account
users    List users currently logged in
uuencode Encode a binary file 
uudecode Decode a file created by uuencode

v        Verbosely list directory contents (`ls -l -b')
vdir     Verbosely list directory contents (`ls -l -b')
vi       Text Editor

watch    Execute/display a program periodically
wc       Print byte, word, and line counts
whereis  Report all known instances of a command    
which    Locate a program file in the user's path. 
while    Execute commands
who      Print all usernames currently logged in
whoami   Print the current user id and name (`id -un')
Wget     Retrieve web pages or files via HTTP, HTTPS or FTP

xargs    Execute utility, passing constructed argument list(s)
yes      Print a string until interrupted

.period  Run commands from a file
###      Comment / Remark