Posts Tagged tips and tricks
April 16, 2009 at 4:05 pm · Filed under Uncategorized ·Tagged admin, deployement, install, linux, pm, project management, redmine, script, scripting, scripts, shell script, sysadmin, system, system administration, tip, tips, tips and tricks, tools, ubuntu
I’ve successfully insalled redmine pretty much easily but I needed to find out what packages to install with apt, which one with gem, which version …
Here is my magic receipe to install it all:
apt-get update
apt-get install subversion mysql-server rubygems rake pwgen
# next line generates a password for the database
export PASSWORD=`pwgen -nc 8 1`
gem install -v=2.1.2 rails
echo "CREATE DATABASE redmine DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci ; GRANT ALL PRIVILEGES ON redmine.* TO 'redmine'@'localhost' IDENTIFIED BY '$PASSWORD' WITH GRANT OPTION; FLUSH PRIVILEGES" | mysql
cd /opt/
svn export http://redmine.rubyforge.org/svn/branches/0.8-stable redmine-0.8
cd redmine-0.8/
cat <<EOF >> config/database.yml
production:
adapter: mysql
socket: /var/run/mysqld/mysqld.sock
database: redmine
host: localhost
username: redmine
password: $PASSWORD
encoding: utf8
EOF
rake db:migrate RAILS_ENV="production"
rake redmine:load_default_data RAILS_ENV="production"
apt-get remove pwgen subversion
RAILS_ENV="production" ./script/server
And that’s it ! Redmine is running on port 3000.
I did this on an EC2 instance and it works like a charm (ami-7cfd1a15).
Maybe next article will discuss running redmine in mongrel or apache, and creating an init script for having redmine running on boot !
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April 14, 2009 at 3:20 pm · Filed under Uncategorized ·Tagged admin, dns, sys, sysadmin, system, system administration, tips, tips and tricks
RFC 952 and RFC 1123 explains the rules for choosing a hostname. I noticed recently that a lot of admins (including me) are using underscores in hostnames, but this doesn’t follow RFCs. This can lead to strange behaviours, such as mail not delivered with an RFC compliant mail server to an MX that have underscores in its name …
I noticed that because the “hostname” command on linux can set the hostname of a system, but the command doesn’t accept underscores. So guys, don’t use underscores !
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April 8, 2009 at 1:57 pm · Filed under Uncategorized ·Tagged mysql, tips, tips and tricks
I just discovered an apparently wide spread tip for mysql:
mysql> select 1, 2, 3, 4 ;
+---+---+---+---+
| 1 | 2 | 3 | 4 |
+---+---+---+---+
| 1 | 2 | 3 | 4 |
+---+---+---+---+
1 row in set (0.00 sec)
mysql> select 1, 2, 3, 4 \G;
*************************** 1. row ***************************
1: 1
2: 2
3: 3
4: 4
1 row in set (0.00 sec)
As you might have seen, the difference comes from the “\G” !
It’s very usefull when you select lot of columns that doesn’t fit the width of your terminal !
Shame on me I didn’t knew that before !
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October 28, 2008 at 2:21 pm · Filed under Uncategorized ·Tagged backup, database, databases, dba, mysql, mysqldump, script, scripting, shell script, shell scripting, sql, sysadmin, system, system administration, tips and tricks
Today I encountered a problem: I needed to restore a single table from a database mysqldump.
Usually you cat the-mysqldump.sql |mysql the_database so you’re only able to restore the full database. I didn’t find any mysqldump option to extract a single table from a full database dump, so I’ve come up with this (minimal) shell script:
#!/bin/sh
extract_table(){
TABLE=$1
DUMPFILE=$2
grepstr="/*!40000 ALTER TABLE \`$TABLE\`"
lines=`grep -n "$grepstr" $DUMPFILE |cut -d":" -f1`
lines=`echo $lines|sed 's/\ /,/' `
echo "LOCK TABLES \`$TABLE\` WRITE;"
sed -n "$lines p" $DUMPFILE
echo "UNLOCK TABLES;"
}
extract_table $1 $2
Use it like this:
./this-script.sh table-to-extract dumfile-for-extract |mysql the_database (use the |mysql after you have checked the content).
Be carefull, this script is minimalistic:
- It doesn’t check if the file exist and is really a mysqldump file
- It doesn’t check if the table to extract exists
- It doesn’t work if disable-keys is set to false in mysqldump
- It doesn’t have a usage() function
If some people request it, I’ll write all these features, but as usual, I wanted to come up with a solution I could already use one hour a ago, and I’m spending time to write this script, let’s do it the faster I can ! 
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October 28, 2008 at 1:31 pm · Filed under Uncategorized ·Tagged linux, script, scripting, shell, shell script, shell scripting, tips and tricks, unix
Let’s say you want to extract a part of a file, for example from line 12 to 20.
I’ve come up with two solutions:
head -n20 |tail -n8
You take the n’th first line where n is the last line you want, then you go backward by the total line number you want to have, that is: 20-12=8- A nicer solution which is straightforward (use the right tools guys !):
sed -n '12,20p'
You need the -n option, so that the input is not printed to the output, than give sed an expression (within quotes), the expression is the first line, a coma, the last line, and the “p” instruction which means print.
This solution doesn’t need you to calculate the number of lines you will get, I find it nicer !
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September 10, 2008 at 12:28 pm · Filed under Uncategorized ·Tagged admin, administration, bind, dns, network, sysadmin, system, tips, tips and tricks, tricks, unix, web
There a some web based bind zone generator, but searching for “zone generator” in google, I found a lot that aren’t working, refining my research didn’t helped me. I finally found one that does the stuff. It’s not optimal , but it work , and it’s there
Please, if you know of a better one, just let me know !
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