Practical deep-dives on Linux, AI, and large language models. 290+ technical articles for developers, sysadmins, and AI engineers.
Gitk is a great tool for working with Git. Unfortunately after setting up git and X11 forwarding I got this error when running gitk.
The error can easily be fixed by installing dejavu-sans-fonts.
yum install -y dejavu-sans-fonts
The result :
Voila !
When installing php PECL On CentOS/RHEL (+cPanel) installations, if you get a “checking whether the C compiler works… configure: error: cannot run C compiled programs”, you may need to remount the /tmp and /var/tmp with exec permissions first:
$ mount -o remount,exec,suid /tmp
$ mount -o remount,exec,suid /var/tmp
Then:
$ pecl install {package}
And, don’t forget to remount them as noexec after.
Run updatedb first. You can run it manually from the command line.
updatedb
It should have scheduled itself as a cron job when you installed slocate. If you just installed slocate, it will not have run yet. Otherwise, make sure you have a cron daemon running and that there is an updatedb task scheduled. Also, make sure your computer is on when it it is scheduled
If this is a VM and does not run continuously especially never spent days on this will happen. Just in case check the cron job found here:
The cron job is found here:
/etc/cron.daily/mlocate.cron
Thats’ pretty much it.
Howto Install no-ip utility in CentOS to fix dynamic ip issues using a subdomain from no-ip.org.
First go to no-ip webpage http://www.no-ip.com
Register and confirm your email, then login your account and add a host. Download the linux client As user root execute:
cd;wget "https://www.no-ip.com/client/linux/noip-duc-linux.tar.gz" tar -xvf noip-duc-linux.tar.gz cd noip-2.1.9-1 make make install
Create a configuration file:
noip2 -C
The script will ask you which ethernet port to use, then write your email account you use to register with no-ip, then the password, finaly choose the host you will be using.
Now lets create init file to wake up the deamon every time we start our box.
cd /etc/init.d nano noip2d
Add the following in noip2d :
# chkconfig: 345 20 80
# description: Starts noip2 deamon to check for dynamic ip \
# and updates new ip to no-ip.org dns cache.
#######################################################
#! /bin/sh
# . /etc/rc.d/init.d/functions # uncomment/modify for your killproc
case "$1" in
start)
echo "Starting noip2."
/usr/local/bin/noip2
;;
stop)
echo -n "Shutting down noip2."
echo "."
for i in `noip2 -S 2>&1 | grep Process | awk '{print $2}' | tr -d ','`
do
noip2 -K $i
done
##killproc -TERM /usr/local/bin/noip2
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
#######################################################
Save and Exit, now lets work on the permits:
chmod +x /etc/init.d/noip2d chmod 700 /usr/local/bin/noip2 chown root:root /usr/local/bin/noip2 chkconfig --levels 3 noip2d on noip2d start
Verify the deamon is running:
ps aux | grep noip2
If everything goes as plan, you have no-ip service in your box and will be updating every time your ip changes.
Finaly try to see your machine in your browser. http://myhostname.no-ip.org
Thanks for reading.
If you have a local script file and want to run the script on another server use the following :
ssh root@torino.maranello.local ‘bash -s’ < script_local.sh
Enjoy 🙂
To work with command line on the Amazon Cloud you need to get hold of the following file which is the EC2-api-tools look for the latest version here :
I used the file found here.
When trying to setup the Amazon EC2 tools you would expect to have some script that asks you key questions and sets up the environment for you.
Well not quite so.
Starting Point is here : Setting Up the Amazon EC2 Command Line Tools
1) Install the Java JDK (Java Development Kit) OR RTE ( Run Time Engine ) found here. For cento select the rpm.
13:30:16-root@controller:~$ yum install jre-7u9-linux-i586.rpm
2) Test the java installation
13:36:56-root@controller:~$ java -version
java version “1.7.0_09”
Java(TM) SE Runtime Environment (build 1.7.0_09-b05)
Java HotSpot(TM) Client VM (build 23.5-b02, mixed mode, sharing)
3) Download and unpack the api tools
13:38:39-root@controller:/tmp$ wget “http://s3.amazonaws.com/ec2-downloads/ec2-api-tools.zip”
13:39:49-root@controller:/tmp$ unzip ec2-api-tools.zip
4) Move it to the user home folder under a new folder e.g. ec2
13:39:52-root@controller:/$ mv /tmp/ec2-api-tools-1.6.4/ ~/ec2/
5) Create a softlink to the new version (used for rewiring later when new versions are installed)
13:39:53-root@controller:/$ ln -s ~/ec2/ec2-api-tools-1.6.4/ ~/ec2/api
Create a shell script with the following environment parameters to tell amazon where the stuff is and who you are:
I add this script to my /etc/profile.d/ec2 since only two users on this machine is me :).
#!/bin/bash export JAVA_HOME=/usr export EC2_HOME=/root/ec2/api export PATH=$PATH:$EC2_HOME/bin export AWS_ACCESS_KEY=XXXXXXXXXXX export AWS_SECRET_KEY=//XXXXXXXXXXXXXXXXX export EC2_URL=https://ec2.eu-west-1.amazonaws.com
Other Documents :
After you build your custom ~/.bash_profile when you use screen it skips the customizations in the ~/.bash_profile file.
Try to edit .screenrc and then add
shell -$SHELL
Howto use enterprise Linux ‘extras’ to mount a XFS filesystem on a CentOS v5.2 VM
Install RPM’s
Note: Due to this bug (3205), install binutils to overcome the error “xargs: nm: No such file or directory” while installing kmod-xfs-xen.
# yum install binutils
# yum install xfsprogs yum-kmod kmod-xfs-xen
# mkfs.xfs -f /dev/sda1
Check
A chunk of disk (2TB) has been allocated to a LVM partition for the VM, which is formatted with XFS. The device is mapped into the VM as /dev/xvdc1 (i.e. a whole device, c.f. partitioned device).
Before using the filesystem, perform a check:
# xfs_check /dev/xvdc1
Note: xfs_check requires a significant chunk of memory to run. With 2Gbyte of swap and 1Gbyte of RAM a check was unsuccessful.
Mount
Mount the disk by using it’s volume label. The label can be verified with the xfs_admin program:
# xfs_admin -l /dev/xvdc1
label = “purple-files”
Add the mount entry to ‘/etc/fstab’ so that the filesystem is automatically mounted at the next restart.
LABEL=purple-files /files xfs defaults 0 0
Mount the filesystem
# mount /files
NOTE: CENTOS 6.X
Centos 6.X (64bit) already supports XFS in kernel. You only need to install xfsprogs package to mount xfs filesystems. just yum install xfsprogs (it is included in centos 6.2 base)
# yum install xfsprogs yum-kmod kmod-xfs-xen
Dependencies Resolved
=============================================================================
Package Arch Version Repository Size
=============================================================================
Installing:
kmod-xfs-xen x86_64 0.4-2 extras 256 k
xfsprogs x86_64 2.9.4-1.el5.centos extras 1.3 M
yum-kmod noarch 1.1.10-9.el5.centos base 15 k
Transaction Summary
=============================================================================
Install 3 Package(s)
Update 0 Package(s)
Remove 0 Package(s)
Total download size: 1.6 M
To search for text through the entire filesystem from the current path down in Linux use the following :
find / -type f -print0 | xargs -0 grep -l "string to search" 2>/dev/null
Listing the mac addresses of nic cards excluding null or loopback MACs i.e. 00:00:00:00:00:00
grep -H . /sys/class/net/*/address | awk ‘{split($0,array,”address:”);print array[2]}’ | grep -v ’00:00:00:00:00:00′