Don Unix - Unix Tips n Tricks

SVN : How to restore an older version of my current file ?

noreply@blogger.com (Fenice) — Mon, 09 Nov 2009 16:26:00 +0000

I want to restore an older version (from the SVN revision number 1289) of my current file fic.pl, what can I do ?

Here is the tips (NB my current revision is 1492) :

[npene@donunix] svn merge -r 1492:1289 fic.pl

[Perl] One liner calculus

noreply@blogger.com (Fenice) — Wed, 29 Jul 2009 12:13:00 +0000

In the following example file « calc.txt », I want to multiply each number by 2/3 :

199,119
326,147
385,345
250,330
157,218
67,241
402,175

Here is the solution in one line with Perl :

[pene@donunix] perl -pi.bak -e 's|(\d+),(\d+)|int($1*2/3).",".int($2*2/3)|e' calc.txt

How to convert a string to upper or lower case ?

noreply@blogger.com (Fenice) — Mon, 20 Jul 2009 09:34:00 +0000

[pene@donunix] var=`echo $var | tr [a-z] [A-Z]`

Twitter : display your rate limit per hour

noreply@blogger.com (Fenice) — Sat, 20 Jun 2009 07:56:00 +0000

[pene@donunix] curl -u twitter_name:twitter_password http://twitter.com/account/rate_limit_status.xml

N.B. : For information, the default rate limit is 100 requests per hour.

grep: advanced use

noreply@blogger.com (Fenice) — Mon, 20 Apr 2009 13:51:00 +0000

How to display all lines with the word text or the word name?
Here is the answer:

[pene@donunix] grep -P 'text|name' file.txt

find and only print files located in subdirectories

noreply@blogger.com (Fenice) — Mon, 06 Apr 2009 13:54:00 +0000

[pene@donunix] find . -maxdepth 2 -mindepth 2

SSH : Public keys generation

noreply@blogger.com (Fenice) — Thu, 19 Mar 2009 08:54:00 +0000

The purpose of this short post is to explain how being connected to an ssh server without typing the password, how ?
With the generation of public ssh keys.

I. Client : Generation of public keys

First (just for the first time) you have to genere the 2 keys :
[donunix@client] ssh-keygen -t dsa

During the dsa key generation, ssh-keygen ask you to enter a path phrase (it replace the password system). type [enter] if you doesn't what to genere a path phrase.

The 2 keys are in the ~/.ssh directory :
[donunix@client] ls ~/.ssh/id_dsa*
id_dsa id_dsa.pub

id_dsa is the private key
id_dsa.pub is the public key to send too the server

Client : send to the server the public keys

copy the public keys to the server :
[donunix@client] scp .ssh/id_dsa.pub user@server:.ssh/client.pub

Server : Record the client public keys

Connect to the server :
[donunix@client] ssh donunix@server

record the keys on the .ssh/authorized_keys file :
[donunix@server] cd .ssh
[donunix@server] cat client.pub >> autorized_keys

And that's all folk ;)
You can now run ssh sessions without typing your password.

[Dvorak keyboard] Launch a XKB keyboard file

noreply@blogger.com (Fenice) — Thu, 05 Mar 2009 15:00:00 +0000

I want to learn the french version of the Dvorak Simplified Keyboard.
To toggle my keyboard from azerty to Dvorak-bepo configuration, I need to launch the dvorak-bepo.xkb file.

So here is, how to set your keyboard in Dvorak-bepo :
[pene@donunix] xkbcomp -w0 fr-dvorak-bepo.xkb :0

And if you want to go back, with the classic French configuration :
[pene@donunix] setxkbmap fr

Enregistrer maintenant

Create a different colored prompt for each users and hosts

noreply@blogger.com (Fenice) — Mon, 02 Mar 2009 15:44:00 +0000

I've just coded this script to avoid mistakes when you're using more than one host and user login :

#!/usr/bin/ksh
#######################################
# Program : Prompt-Color
#
# Version : V1.0
# Date : 2009-03-02
# Author : N. PENE
#
# Inputs : none
#######################################
hostname=`hostname`
username=`whoami`

#-- classic colors vars :
BLACK='\[\033[0;30m\]'
RED='\[\033[0;31m\]'
GREEN='\[\033[0;32m\]'
BROWN='\[\033[0;33m\]'
BLUE='\[\033[0;34m\]'
PURPLE='\[\033[0;35m\]'
CYAN='\[\033[0;36m\]'
GRAY='\[\033[0;37m\]'
DEFAULT='\[\033[0m\]'
#-- bolded colors vars :
BBLACK='\[\033[1;30m\]'
BRED='\[\033[1;31m\]'
BGREEN='\[\033[1;32m\]'
BBROWN='\[\033[1;33m\]'
BBLUE='\[\033[1;34m\]'
BPURPLE='\[\033[1;35m\]'
BCYAN='\[\033[1;36m\]'
BGRAY='\[\033[1;37m\]'
BDEFAULT='\[\033[1;0m\]'

cprompt=$DEFAULT
cborder=$DEFAULT
cpath=$DEFAULT

#-- username color :
case $username in
"npene" ) cuser=$CYAN;;
"donunix" ) cuser=$BLUE;;
"fenice" ) cuser=$PURPLE;;
"donpene" ) cuser=$BROWN;;
"root" ) cuser=$GREEN;;
esac

#-- hostname color :
case $hostname in
"host1" ) chost=$BRED;;
"host2" ) chost=$BBLUE;;
esac

PS1="$cborder[$cuser\u$cborder@$chost\h$cborder: $cpath\W$cborder] $cprompt"
export PS1

convert a pdf file to png files

noreply@blogger.com (Fenice) — Sun, 01 Mar 2009 18:51:00 +0000

[pene@donunix] convert -resize 540x700 fic.pdf fic%04d.png

audio files : increase the volume by +2db

noreply@blogger.com (Fenice) — Sun, 01 Mar 2009 18:47:00 +0000

[pene@donunix] mp3gain -r -d 2.0 mysong.mp3

print the exact date, one week ago

noreply@blogger.com (Fenice) — Tue, 17 Feb 2009 16:05:00 +0000

[pene@donunix] date +'%Y %m %d' --date '1 week ago'

NB : The output format of this command is : YYYY MM DD (2009 02 10)

Script : keep your connection on a remote shell

noreply@blogger.com (Fenice) — Wed, 11 Feb 2009 15:49:00 +0000

A script to launch if you doesn't want to be disconnected by timeout on your remote ssh connection :

#!/usr/bin/ksh
#####################################################################
# Program : Keep-Hand
#
# Version : V2.0
# Date : 2009-02-11
# Author : N. PENE
#
# Inputs : none
#####################################################################

while [ 1 -eq 1 ] ; do

#-- check if the code is attached to an xterm :
term=`ps -p $$ | cut -d " " -f 2`
if [ $term == "?" ] ; then
exit
fi

#-- wait 4min :
sleep 240
echo -e ".\c"
done

SVN : remove all deleted files

noreply@blogger.com (Fenice) — Wed, 11 Feb 2009 10:31:00 +0000

Hi folks,
Today a new Subversion tips: How to remove from the SVN base deleted files (by rm command).

[pene@donunix] svn status | grep '^\!' | sed 's/! *//' | xargs -I% svn rm %

ncftpput : copy a directory

noreply@blogger.com (Fenice) — Mon, 08 Dec 2008 15:56:00 +0000

Here is my reminder, to record one for all the true ncftpput syntax:

[pene@donunix] ncftpput -R -u remote_login -p remote_pass remote_host remote_directory/ local_directory

kill all process unattached to a terminal

noreply@blogger.com (Fenice) — Thu, 20 Nov 2008 09:00:00 +0000

I need to kill a lots off process running called "keep-hand.ksh".
The problem: I don't want to kill "keep-hand.ksh" process attached to a Terminal (TTY).
The challenge: Doing it, in one line!

My answer:
[pene@donunix] ps -u pene | grep keep-hand.ksh | grep ? | cut -d "?" -f 1 | xargs kill -9

[NCO] extract a smaller area in a netCDF file

noreply@blogger.com (Fenice) — Wed, 15 Oct 2008 13:53:00 +0000

I want to create a smaller area with these new dimentions :
For the x coordinate : [1,300]
For the y coordinate : [ 250,800]

[pene@donunix] ncks -dx,,200 -dy,250,800 fic_in.nc fic_out.nc

[NCO] concatenate 2 netcdf files with differents variables

noreply@blogger.com (Fenice) — Wed, 15 Oct 2008 13:38:00 +0000

In two steps :

[pene@donunix] ncecat fic_in1.nc fic_out.nc
[pene@donunix] ncecat -A fic_in2.nc fic_out.nc

Make a list of your twitter friends

noreply@blogger.com (Fenice) — Sat, 06 Sep 2008 10:29:00 +0000

Make lists of your twitter friends and followers :

friends :

[pene@donunix] curl -u twitter_name:twitter_password -d status="friends" http://twitter.com/statuses/friends.xml | grep screen_name | sort | sed -e 's/ * $.*$<\/screen_name>/\1/' > friends.xml

followers :

[pene@donunix] curl -u twitter_name:twitter_password -d status="followers" http://twitter.com/statuses/followers.xml | grep screen_name | sort | sed -e 's/ *$.*$<\/screen_name>/\1/' > followers.xml

How to post on twitter from a Unix console !

noreply@blogger.com (Fenice) — Fri, 25 Jul 2008 08:33:00 +0000

Its really simple to do it with curl :
[pene@donunix] curl -u twitter_name:twitter_password -d status="$1" http://twitter.com/statuses/update.xml

and, if like me you're in front of the proxy problem :
[pene@donunix] curl -x http://proxyurl:proxyport -U proxy_username -u twitter_name:twitter_password -d status="$1" http://twitter.com/statuses/update.xml

[Perl] make changes form line 3 to line 20

noreply@blogger.com (Fenice) — Fri, 23 May 2008 14:35:00 +0000

How to substitute all pattern1 to pattern2 from the 3rd line to the 20st line?
Perl has the solution... and in one line :D

[pene@donunix] perl -p -i -e "s|pattern1|pattern2| if 3 .. 20" file.txt

Find all running process named "firefox"

noreply@blogger.com (Fenice) — Thu, 08 May 2008 23:49:00 +0000

Find for the user pene all running process named "firefox"

[pene@donunix] ps -u pene | grep firefox

[Shell-Script] create a lock system for your code

noreply@blogger.com (Fenice) — Mon, 28 Apr 2008 07:47:00 +0000

Here is the code for making a lock system in your shell-script program.
The main utility of the lock system is to be sure to not running your code while another process of the same code is running.

The main principe is to create a lock file when the code is running, and check the existance of this file each time you're launching it.

NB : the variable $exec is the name of the script you want to execute.

#-- Parameters:
exec="./my-script.sh"
NAME="my-script"
LOCK="/tmp/${NAME}.lock"
out="/tmp/${NAME}-$(/bin/date '+%Y%m%d').out"

#-- Error Function:
error () {
echo "$1" 1>&2
exit 1
}

#-------------------------
# Launch the code
#-------------------------
if [ -f "$LOCK" ]
then
if [ "$(ps -p `cat $LOCK` | wc -l)" -gt 1 ]; then
#-- process is still running
echo "Quit at start: lingering process `cat $LOCK`"
error "Daemon already running (not launched)!"
exit 10
else
#-- process not running, but lock file not deleted
echo "process not running, but lock file not deleted"
rm $LOCK
echo $$ >> "$LOCK"
fi
else
echo "create lock"
echo $$ >> "$LOCK"
echo "done (pid=$$)"
# launch the code:
ksh ${exec} >> $out 2>&1

fi

rm $LOCK

Find out Linux version

noreply@blogger.com (Fenice) — Mon, 14 Apr 2008 07:16:00 +0000

With LSB (Linux Standard Base) you can know the name of your linux distribution ,the version and the version code name :

[pene@donunix] lsb_release -a

[SVN] Add Recursively

noreply@blogger.com (Fenice) — Thu, 10 Apr 2008 07:54:00 +0000

Here is the command to add recursively new files in Subversion :

[pene@donunix] svn status | grep '^\?' | sed -e 's/^? *$.*$/\1/;s/ /\\ /g' | xargs svn add