Linux Tips

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1. Know the System Installation Date

You can use tune2fs to know the installation date of your Linux System, be ware the /dev/sda[] should be the root partition of your disk. See my following example:

tune2fs -l /dev/sda1 or /dev/sdb1* | grep 'Filesystem created:'
$ sudo tune2fs -l /dev/sda2  | grep 'Filesystem created:' 
Filesystem created:       Mon May  5 17:31:40 2014

2. View Thread Status

View the thread status via proc filesystem.

$ ps -ef | grep conky
Trusty      1396     1  0 19:15 ?        00:00:03 conky
Trusty      7410  6161  0 19:23 pts/5    00:00:00 grep --color=always conky
$ cd /proc/1396/task
$ ls
1396  1397  1398  1399  1400  1401  1402  1403
$ cat 1396/status| grep "State"
State:	S (sleeping)

3. Write to other users

Use w to get the tty, then write to other users.

root@lilimarleen:/# w
 00:47:04 up 28 min,  2 users,  load average: 0.00, 0.01, 0.02
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
root     pts/0    1xx.xxx.xxx.xxx  00:26    0.00s  0.08s  0.00s w
root     pts/2    18x.xxx.xxx.xx   00:40   32.00s  0.03s  0.03s -bash
root@lilimarleen:/# echo "Hi, LiliMarleen">/dev/pts/2
root@lilimarleen:/# echo "Do you have lunch">/dev/pts/2

4. Share Terminals

Make sure the screen command is available on your machine, then:
Server side:

$ screen -S share

Client side:

$ screen -x share

Now both side input could be seen.

5. Create xz file

xz file will greatly decrease the file size, we use following command for create a xz file:

tar cvfJ tar_xz_file.tar.xz folder_or_file

extract from xz from could be:

tar -xJf tar_xz_file.tar.xz

6. Login issue

When you met

file /home/xxx/.Xauthority does not exist

simply run following command once you login:

$ startx

Next time you won’t met this complains.

7. Execution priviledge

Login to Opensuse, run ifconfig will complains it needs root priviledge:

Absolute path to 'ifconfig' is '/sbin/ifconfig', so running it may require superuser privileges (eg. root)

Simply add one line to the end of your ~/.bashrc file:

export PATH=/sbin/:$PATH

Next time you could directly run ifconfig, or if you don’t want to change your .bashrc file, do /sbin/ifconfig.

8. Show history timestamp

[Trusty@Linux01 ~]$  export HISTTIMEFORMAT="%F %T `whoami` "
[Trusty@Linux01 ~]$ history | more
    6  2014-10-29 03:33:01 Trusty ls | grep trb
    7  2014-10-29 03:33:01 Trusty ./trbTest.py 
    8  2014-10-29 03:33:01 Trusty history |grep export
    9  2014-10-29 03:33:01 Trusty su root

9. Vrome setting

Chromium install the vrome then set the options of

set useletters=0

The keyshorts: go to address line Ctrl+L, in MAC Win+L.

10. Replace the word until end of the line

In vim by following command:

:%s/\<foo\>.*//
On each line, delete the whole word "foo" and all following text (to end of line).

11. Managing all of the running vagrants

See following command:

[Trusty@/media/y/Vagrant/vccw/myproxy/vccw-1.9.1]$ VBoxManage list runningvms
"vccw-191_default_1417846604747_55987" {7b802d9e-dee2-4662-9694-e7cff6cbc49b}
[Trusty@/media/y/Vagrant/vccw/myproxy/vccw-1.9.1]$ VBoxManage controlvm vccw-191_default_1417846604747_55987 savestate
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

12. Battery

To know the current battery via acpi, run:

$ acpi -b

To know the more detailed info of Battery, goto:

$ cd /sys/class/power_supply/BAT0

13. Add arp entry

So if you have rebooted the existing testing environment, your arp entries may be lost, simply use following command for adding it:

$ arp -s 192.168.1.10 00:01:02:03:04:05

Now you will directly reached 192.168.1.10 via the specified mac address.

14. Enable opera proxy

After Opera upgraded to latest version its configuration for proxy is failed, so I change the startup command from opera to:

$ opera --proxy-server="socks://127.0.0.1:1395"
$ alias opera='opera --proxy-server="socks://127.0.0.1:1395"'

15. Delete a package and its configuration file

Use pacman -R --help for more detailed infos, so remove the vagrant including its configuration will be:

$ sudo pacman -R vagrant -n

16. Install rar/unrar on CentOS

Install the rar/unrar via following command:

#  wget http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.i686.rpm
#  sudo rpm -ivh rpmforge-release-0.5.2-2.el6.rf.i686.rpm
#  sudo yum install rar unrar

17. zsh History

The default installed zsh has no history record, thus we have to enable the history via following setting:

$ touch $HOME/.zsh_history
$ tail ~/.zshrc
# For setting zsh history
HISTFILE=$HOME/.zsh_history
setopt INC_APPEND_HISTORY
setopt SHARE_HISTORY
HISTSIZE=5000
SAVEHIST=5000

Now you will got the history recorded for 5000 lines, and each of them could be shared to each other.

18. Calculate Code Lines

We could use cloc for calculate the code lines. In Ubuntu, simply run following commands for installing cloc:

$ sudo apt-get install cloc

cloc via following command:

$ cloc Your_Source_Code_Directory

After a while your statistics result will be displayed on the screen.

19. CMAKE prefix

For specify the cmake’s prefix we use following command:

$ cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr ./ && make && sudo make install

20. xclip

Sometimes we have to quickly redirect some output from the system output to system clipboard, we use xclip, add following alias to your ~/.bashrc or ~/.zshrc:

# Alias the xclip for directly to my system buffer, thus we could use shift+insert for copy the content.
alias myclip='xclip -selection clipboard'

21. Virtualbox Fixed Address

The host-only adapter should have the static addresses, thus you won’t mix each other.

$ sudo vim /etc/network/interfaces
auto eth1
iface eth1 inet static
    address 192.168.56.101
    netmask 255.255.255.0
    gateway 192.168.56.1

22. Autologin Using ssh

When you add the rsa content into the ~/.ssh/authorized_keys, but you still can’t auto-login, then you have to consider the priviledge problem:

$ ls ~/.ssh/authorized_keys  -l 
-rw-r--r--. 1 Trusty Trusty 392 Feb 11 11:36 /home/Trusty/.ssh/authorized_keys
$ chmod g-w ~/.ssh/authorized_keys

Now you could reach the machine without inputting password.

23. Change Static Address For CentOS

Change the following file:

$ sudo vim /etc/sysconfig/network-scripts/ifcfg-eth*
DEVICE=eth0 
BOOTPROTO=none 
ONBOOT=yes 
NETWORK=10.0.1.0 
NETMASK=255.255.255.0 
IPADDR=10.0.1.27 
USERCTL=no

Restart and then you could find your CentOS have static address.

24. Disable Touchpad

First use xinput list for list all of the input devices for X, then set the property of them via:

$ xinput list
⎡ Virtual core pointer                          id=2    [master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)]
⎜   ↳ Logitech USB Optical Mouse                id=9    [slave  pointer  (2)]
⎜   ↳ PS/2 Generic Mouse                        id=12   [slave  pointer  (2)]
⎜   ↳ SynPS/2 Synaptics TouchPad                id=13   [slave  pointer  (2)]

......

$ xinput set-prop 13 "Device Enabled" 0


25. visudo

Sometimes in the visudo we set NOPASSWD, but it didn’t take effects, why? because you are belong to some groups, while these group rules overwrite the previous rules you set, simply change all of the corresponding rules to:

NOPASSWD:ALL

Save the file and now you will see sudo command won’t ask you input anything.

26. Youtube download

Ubuntu could directly download youtube videos via install youtube-dl:

$ sudo apt-get install youtube-dl

27. perl-rename

As ArchLinux’s default rename tool is very simple use following rename tools provided via perl:

$ sudo pacman -S perl-rename
$  vim ~/.zshrc
### The default rename didn't support regex, use perl-rename instead.
alias rename='perl-rename'


28. udiskie

udiskie is for automatically mount/umount usb disks, but the ubuntu won’t support it in official repository, we could install it via:

$ sudo pip install udiskie

mount and umount disks via:

$ sudo udiskie-mount -a
$ sudo udiskie-umount -a

29. git merge conflicts

Sometimes when you git pull from remote repository, you will got some anoying hint messages which shows you have merge conflicts, following is the steps for solving this issue:

$ git pull
$ git stash
$ git pull

Now you are ready to work under merged trees.

30. Git remote repository

When first git clone to local, then git push origin master, it will complains:

[Trusty@~/Code/herokublog]$ git push origin master
fatal: remote error: 
  You can't push to git://github.com/xxxx/herokublog.git
  Use https://github.com/xxxx/herokublog.git
[Trusty@~/Code/herokublog]$ ssh -T git@github.com
X11 forwarding request failed on channel 0
Hi xxxx! You've successfully authenticated, but GitHub does not provide shell access.
[Trusty@~/Code/herokublog]$ git remote set-url origin git@github.com:xxxx/herokublog.git

After setting this, we could use git push origin master for submitting our changes.

31. Replace all of the strings under one folder

Simply use sed for replacing these strings:

Trusty@MassTestOnUbuntu1404:~/charms/trusty$ grep -rl "http://archive.ubuntu.com" ./ | wc -l
3
Trusty@MassTestOnUbuntu1404:~/charms/trusty$ grep -rl "http://archive.ubuntu.com" ./ | xargs sed -i 's|http://archive.ubuntu.com|http://http://mirrors.aliyun.com|g'
Trusty@MassTestOnUbuntu1404:~/charms/trusty$ grep -rl "http://archive.ubuntu.com" ./ | wc -l
0
Trusty@MassTestOnUbuntu1404:~/charms/trusty$ grep -rl "http://mirrors" ./ | wc -l
3

32. Use local LXC repository

So, let's say you downloaded the ubuntu trusty amd64 tarballs, you need to do:
 - mkdir -p /var/cache/lxc/download/ubuntu/trusty/amd64/default/
 - copy rootfs.tar.xz in /var/cache/lxc/download/ubuntu/trusty/amd64/default/
 - unpack the content of meta.tar.xz in /var/cache/lxc/download/ubuntu/trusty/amd64/default/
 - Then run the download template with: -d ubuntu -r trusty -a amd64

33. Use rsync for syncing the files

$ rsync -e 'ssh -p 1234' username@hostname:SourceFile DestFile
Example:    
$ rsync -avH --progress '-e ssh -p 2223' Trusty@1xx.xxx.xxx.xxx:/home/Trusty/charms/trusty/ ~/charms/trusty/

34. Use dmidecode to view your hardware configuration

dmidecode is a tool-set for dump out your SMIBIOS configuration in readable format, use following command for readout the maximum support moemory of your system, and the already installed memory information on your system:

$ sudo dmidecode -t 16
$ sudo dmidecode -t 17

35. Use fslint for searching out the duplicated files

fslint could search the directory and find out the duplicated files.
Install it via:

$ sudo apt-get install fslint
$ fslint-gui

36. Limitation Bandwidth

Use following command could limit the specified userspace programs’ bandwidth:

$ trickle -s -d 50 -w 100 firefox
http://stackoverflow.com/questions/10328568/simulate-limited-bandwidth-from-within-chrome

37. Grep with color

grep’s default output is without colorful output, do following for enable the colorful output:

alias grep='grep --color=always'

Add this into your .zshrc, so everytime it boots up the grep will output with colors.

38. RaspberryPI items

For optimize the RaspberryPI, need to do following:

relatime/atime, use relatime
cat /sys/block/mmcblk0/queue/scheduler/
noop deadline cfq
use noop
[noop] deadline cfq

39. Install OpenStack On CentOS

The following tips:

   35  packstack --answer-file=/root/answer.txt
   41  cat /etc/sysconfig/selinux
   42  vim /etc/selinux/config
Disable selinux, then try it again

<<<<<<< HEAD

40. Install OpenContrail/OpenStack

https://fosskb.wordpress.com/2014/10/18/openstack-juno-on-ubuntu-14-10/

https://techwiki.juniper.net/Documentation/Contrail/Contrail_Controller_Getting_Started_Guide/10_In_Context%3A_Contrail_Controller_Getting_Started_Guide

40. Docker save/load

In the server, do:

docker save ubuntu>/root/myubuntu.tar

Scp it to client machine, and in client machine, do:

docker load</root/myubuntu.tar

Examine it via:

[root@10-17-17-183 ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
ubuntu              latest              d0955f21bf24        2 weeks ago         188.3 MB

41. Build Maas Based CentOS Image

Following is just the commands:

root@pc121:~/iso/CentOSImage/maas-image-builder# #./bin/maas-image-builder -o centos6-amd64-root-tgz centos --edition 6                        
root@pc121:~/iso/CentOSImage/maas-image-builder# pwd
/home/clouder/iso/CentOSImage/maas-image-builder


58372fecc80eeda12cddd4001534fc541cab8f30

42. View multiply errors

For displaying all of the error/warnings.

for file in $(ls /var/log/nova/); do cat /var/log/nova/$file | grep -iE 'error|warn' ; done

43. Reference for docker and contrail

http://www.opencontrail.org/docker-with-opencontrail/

44. Run Jobs at certain time

Following is an example for automatically download the iso file at the spare time of the office network.

# echo "wget http://mirrors.aliyun.com/ubuntu-releases/15.04/ubuntu-15.04-server-amd64.iso -O /home/juju/iso/ubuntu-15.04-server-amd64.iso " | at 12:27

45. Check kvm

We could use kvm-ok for checking your cpu is compatible for use kvm acceleration.

$ sudo apt-get install cpu-checker
$ kvm-ok

The output will shows whether your cpu support kvm or not.

46. Quickly Installation the Desktop

Turn your minimal CentOS into a full Desktop:

$  sudo yum install system-config-kickstart
$  sudo yum install gnome-desktop
$  sudo yum -y groupinstall "X Window System" "Desktop"

Enter the desktop via startx

47. Restart bluetooth in Ubuntu

Sometimes the bluetooth will fail on Ubuntu, using following command for restart the bluetooth service:

$ sudo /etc/init.d/bluetooth restart

Now you could continue to detect the devices and setup the configuration.

48. Control the network flow

Use wondershapt for controlling the network flow:

# wondershaper eth0 3000 500

The first parameter is the download rate, while the second parameter is the upload rate..

49. Can’t git remote

You should edit the remote branch like following to enable the git push origin:

$ git push origin master
fatal: remote error: 
  You can't push to git://github.com/User/xxx.git
  Use https://github.com/User/xxx.git
  Use https://github.com/purplepalmdash/NewBlog.git
$ git remote rm origin
$ git remote add origin git@github.com:User/xxx.git
$ git push origin master

50. Quickly Setup NFS Server

On Ubuntu, first install the nfs-server:

$ sudo apt-get install nfs-kernel-server
$ sudo vim /etc/exports 
/media/repo     192.168.1.0/255.255.255.0(rw,sync,no_subtree_check)
$ sudo /etc/init.d/nfs-kernel-server restart

Mount it via:

$ sudo mount -t nfs 192.168.1.13:/media/repo /mnt

51. Set Aliyun For CentOS7

Run following commands will update the CentOS repository and import the epel repository for CentOS7

# mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
# yum makecache
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
# yum  -y  update

52. Set apt-proxy for Ubuntu

If you have set the apt-proxy, remember the listening port is:

$ cat /etc/apt/apt.conf
Acquire::http::Proxy "http://10.3.3.5:3142"

The configuration for apt-proxy could be found via google.

54. Use gem taobao source

For avoiding the GFW.

/opt/chef/embedded/bin/gemsources -a http://ruby.taobao.org/

53. Use Aliyun Repository

gem source -r https://rubygems.org/
gem source -a http://mirrors.aliyun.com/rubygems/

54. XDMCP Error

 XDMCP fatal error: Session declined Maximum number of open sessions from your host reached from .

[root:~]# cat /etc/gdm/custom.conf
[xdmcp]
Port=177
+ DisplaysPerHost=5
Enable=true

# reboot

Now your client will successfully login to the remote server.

55. Upgrade Ubuntu14.04.2 Kernel

For upgrade it to 3.16.xxx, simplying use following command:

$ sudo apt-get install linux-image-generic-lts-utopic

56. Install Docker on Ubuntu

$ wget -qO- https://get.docker.com/ | sh

57. Permanent Change Hostname on Fedora

$ sudo hostnamectl set-hostname --static "YOUR-HOSTNAME-HERE"

58. Remote VNC via SSH

Home machine:     
ssh -R *:6234:localhost:5901 xxxx@1xxx.xxx.xxx.xxx -p xxxx4

Server, forward 6234 to 16234:    
ssh -NfL *:16234:localhost:6234 localhost -p xxxx4

Company:    
vncviewer 1zxxx.xxx.xxx.xxx:16234

59. Disable byobu from scrolling

This is because the byobu use tmux for the backend. Change it into screen.

$ byobu-select-backend 
# and selecting screen (option 2).

60. Add items into the host file

# ifconfig | awk -v MYHOST=$(hostname) '/inet addr/{print substr($2,6),"\t",MYHOST}'>>/etc/hosts

61. GPG Issues

https://help.ubuntu.com/community/GnuPrivacyGuardHowto#Using_GnuPG_to_generate_a_key

62. Mirror Whole Website

Use Wget for retrieving all of the items:

[root:/home/juju/Fuel61Repository]# wget --recursive -c -np -k -L http://mirror.fuel-infra.org/

63. Grouplist for yum

yum install the group of the X window System, thus we could forwarding X11.

$ sudo yum grouplist
$ sudo yum groupinstall "X Window System"