Sleeping for a random amount of time in a shell script

You can use the special $RANDOM environment variable to get a random number and divide it by the maximum number of seconds that you want to wait. Use the remainder as the number of seconds to sleep since it will always be between zero and the max you specified. This example will sleep anywhere between zero and 10 minutes (600 seconds)

 /bin/sleep/sleep   `/usr/bin/expr $RANDOM % 600`

Purists will note that it isn’t truly random. The maximum value for $RANDOM is 32767 which is not evenly divisible by most likely values, but it is close enough.

Installing SVN and Trac on a CentOS 5 server

Make sure that you have the RPMForge repository enabled. Install Subversion, mod_dav_svn, and trac. This will install a few required dependencies (ie: neon and some python utils)

# yum install subversion mod_dav_svn mod_python trac

Create a directory for your repositories, and an initial repository for testing, and create your htpasswd file. Then create a trac environment and set it up.

# mkdir /home/svn/
# svnadmin create testrepo
# chown -R apache:apache /home/svn/*
# htpasswd -c  /home/svn/.htpasswd brandon

#mkdir /home/trac/
# trac-admin /home/trac/ initenv
    ... answer questions as appropriate ...
# chown apache:apache /home/trac/*
# htpasswd -c  /home/svn/.htpasswd brandon

Add this to your Apache configuration in the relevant place (I like to put it under an SSL VirtualHost)

    <Location /svn>
        DAV svn
        SVNParentPath /home/svn/
        #SVNListParentPath on
        # Authentication
        AuthType Basic
        AuthName "RoundSphere SVN Repository"
        AuthUserFile /home/svn/.htpasswd
        Order deny,allow
        Require valid-user
    <Location /trac>
        SetHandler mod_python
        PythonHandler trac.web.modpython_frontend
        PythonOption TracEnv /home/trac
        PythonOption TracUriRoot /trac
        # Authentication
        AuthType Basic
        AuthName “MyCompany Trac Environment"
        AuthUserFile /home/svn/.htpasswd
        Require valid-user

Now test to make sure that you can view your test repository in a browser and that it prompts for a username and password as desired:


You should retrieve a plain looking page that mentions the name of your repository and that it is at Revision 0

You should also be able to access your trac installation at


Customize your logo, change the home page, start making some tickets, using the wiki and get to work.

Pear Upgrade Installer

I was trying to install PHPUnit today, but the box wouldn’t allow me because the Pear Installer version wasn’t current. But there was no obvious way to upgrade the pear installer.

[root@ci /]# pear install phpunit/PHPUnit
Did not download optional dependencies: pear/Image_GraphViz, pear/Log, channel://, use --alldeps to download automatically
phpunit/PHPUnit requires PEAR Installer (version >= 1.8.1), installed version is 1.4.9
phpunit/PHPUnit can optionally use package "pear/Image_GraphViz" (version >= 1.2.1)
phpunit/PHPUnit can optionally use package "pear/Log"
phpunit/PHPUnit can optionally use package "channel://" (version >= 1.0.2)
phpunit/PHPUnit can optionally use PHP extension "json"
phpunit/PHPUnit can optionally use PHP extension "xdebug" (version >= 2.0.5)
No valid packages found
install failed

The trick is to install the PEAR package with –force to make it go through

[root@ci /]# pear upgrade --force PEAR
warning: pear/PEAR dependency package "pear/Archive_Tar" installed version 1.3.6 is not the recommended version 1.3.3
warning: pear/Archive_Tar requires PEAR Installer (version >= 1.5.4), installed version is 1.4.9
downloading PEAR-1.9.0.tgz ...
Starting to download PEAR-1.9.0.tgz (291,634 bytes)
.............................................................done: 291,634 bytes
downloading Archive_Tar-1.3.6.tgz ...
Starting to download Archive_Tar-1.3.6.tgz (17,600 bytes)
...done: 17,600 bytes
upgrade ok: channel://
upgrade ok: channel://
PEAR: Optional feature webinstaller available (PEAR's web-based installer)
PEAR: Optional feature gtkinstaller available (PEAR's PHP-GTK-based installer)
PEAR: Optional feature gtk2installer available (PEAR's PHP-GTK2-based installer)
To install use "pear install pear/PEAR#featurename"

From there, you can continue on the the PHPUnit Install