Useful Linux howtos

Applications

to install Oracle Java JDK follow these instructions;
to compare files or directories use “Meld Diff Viewer”. You can install it by running:
```
sudo apt-get install meld
```

to install Microsoft’s Core Font package run:

sudo apt-get install ttf-mscorefonts-installer

to synchronize folders, files and make backups use “Conduit Synchronizer”. You can install it by running:
```
sudo apt-get install conduit
```
to change grub settings (e.g. to change your default operating system, etc) install “StartUp Manager” by running:
```
sudo apt-get install startupmanager
```
to automatically mount at boot your NTFS partitions install “Storage Device Manager” by running:
```
sudo apt-get install pysdm
```
to set up a repository cache on your network so that once a package is downloaded from an official repository, all other machines will download it from your local area network, install squid-deb-proxy (and its client so the server downloaded updates get cached by the squid proxy and will also allow the server to install already-fetched updates via the proxy) on your server machine by running:
```
sudo apt-get install squid-deb-proxy squid-deb-proxy-client
```
then reboot your server machine. Clients can auto-discover caching-enabled machines in the local network by having the squid-deb-proxy-client package installed. To do that simply run:
```
sudo apt-get install squid-deb-proxy-client
```

Information

to know your IP address:
```
ifconfig | grep Bcast
```
to know your hardware details and save them in an html page run:
```
lshw -html > your-file-name.html
```
(a good idea is to generate one for each of your computers and save them up for future reference)
to check whether a certain package is installed:
```
dpkg -l | grep packagename
```
to know whether you need to reboot a machine after updating the system via terminal check if the following file exists:
```
/var/run/reboot-required
```
to test the speed of your hard drive run:
```
sudo hdparm -t /dev/sd?
```
to list running services run:
```
sudo netstat -tulpn
```
to check RAM speed, size and frequency:
```
sudo dmidecode --type 17 | more
```
to know your processor details run:
```
cat /proc/cpuinfo | grep name
```

to know the bios version of your motherboard run:

sudo apt-get install smbios-utils
sudo smbios-sys-info

to know the name of the Linux distribution installed on your machine run:
```
lsb_release -a
```
or, if that doesn’t work then run:
```
cat /etc/issue
```
to have some system information of your machine run:
```
uname -a
```
to see if your operating system architecture is 32-bit or 64-bit run:
```
file /sbin/init
```
to list all users in your system from terminal, run:
```
cat /etc/passwd | grep "/home" |cut -d: -f1
```

Operations

to configure your terminal commands history add one or more of the following lines to your ~/.bashrc file:
- to change name of the file in which command history is saved:
```
export HISTFILE=
```
  (the default value is ~/.bash_history)
- to not save in the history certain command lines add them as a colon-separated list:
```
export HISTIGNORE=
```
- to not save a line matching any other previous entry in the history:
```
export HISTCONTROL=ignoreboth
```
- to change the number of commands to remember in the command history:
```
export HISTSIZE=500
```
  (the default value is 500)

to add aliases system-wide you need to edit the file /etc/bash.bashrc For example, the following alias will provide a comprehensive update and clean operation:

alias apt-update='sudo apt-get -f install
&& sudo apt-get autoremove -y
&& sudo apt-get autoclean -y
&& sudo apt-get clean -y
&& sudo apt-get update 
&& sudo apt-get upgrade -y --fix-missing'

to boot in text mode instead of graphical mode (GUI) open the /etc/default/grub file, locate the following line:
```
GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash“
```
and change it to:
```
GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash text“
```
and don’t forget to run ‘update-grub’ afterwards to update. If you need the graphical interface you can still have it by simply running “startx” once logged in.
to keep your computer’s time accurate follow these instructions;

to install fonts for system-wide run:

mkdir /usr/share/fonts/truetype/myfonts
cp [fonts] /usr/share/fonts/truetype/myfonts
fc-cache -f -v

to add a new user via terminal run:
```
sudo adduser username
```
to add a group to a userrun:
```
sudo adduser username groupname
```

to modify the groups of a userrun:

sudo usermod -G comma,separated,list,of,groupnames username

some useful command line shortcuts:
- Ctrl-D: exit from the current session;
- Ctrl-R: searching through the command history;
- Ctrl-A: moves the cursor to the beginning of the command line;
- Ctrl-E: moves the cursor to the end of the command line;
- Ctrl-W: deletes the word immediately before the cursor;
- Ctrl-K: deletes everything immediately after the cursor;
- Ctrl-Y: undo a deletion.
to start a terminal maximized use the command
```
gnome-terminal --window --maximize
```
to start a terminal in full screen use the command
```
gnome-terminal --full-screen
```
to copy multiple files using scp use it like showed below:
```
scp {file1,file2,file3} user@destination:~/
```
to speed up the ssh connection add “UseDNS no” (without quotation marks) at the end of your /etc/ssh/sshd_config and then run:
```
sudo /etc/init.d/ssh reload
```
to add a new resolution to your monitor/display/screen run (assuming you want to add 1600×900):
```
cvt 1600 900
```
that will output something like this:
```
Modeline "1600x900_60.00" 118.25 1600 1696 1856 2112 900 903 908 934 -hsync +vsync
```
Copy the text following Modeline and paste it in the following command:
```
xrandr --newmode "1600x900_60.00" 118.25 1600 1696 1856 2112 900 903 908 934 -hsync +vsync
```
Then run the command xrandr alone:
```
xrandr
```
and note down the connected primary video source (should something like VGA-0, or VGA1). Supposing it’s VGA-0 then run:
```
xrandr --addmode VGA-0 "1600x900_60.00"
```
to open/extract an eml file install munpack:
```
sudo apt-get install mpack
```
then run:
```
munpack filename.eml -t
```

to chmod 775 sub-directories, files excluded:

find /path/to/base/dir -type d -exec chmod 775 {} +

to chmod 664 files recursively, sub-directories excluded:

find /path/to/base/dir -type f -exec chmod 664 {} +

Marco Lackovic

Ph.D., Research Fellow, Teaching Assistant and Programmer

Applications

Information

Operations

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