Linux on Aamnah - Frontend Web Developer

Enable macOS like touchpad gestures on Ubuntu

Wed, 09 Oct 2019 23:54:51 +0500

NOTE: i ended up finally learning how to properly use Workspaces in Ubuntu and no longer use the swipe gesture. They were wonky anyway, middle click was still pasting things in the end.. The touchpad on a Lenove Thinkpad is good, better than any HP or Acer i have ever used, but still doesn’t compare to one on a MacBook

FYI:

I’m using the touchpad of a Lenovo T450.
On my Mac, i use 3-finger swipe up for app Expose, and 3-finger left/right to switch between full-screen apps

Installation and setup

Add yourself to the input group.

Add missing Monitor Resolution profile

Mon, 21 Jan 2019 00:00:00 +0500

tl;dr

get Modeline cvt 1366 768
create and add new mode with xrandr based on the generated modeline
add settings to ~/.xprofile to preserve them, so the settings are still there when you restart

1# Add 1366x768@60Hz
2xrandr --newmode "1368x768"  85.86  1368 1440 1584 1800  768 769 772 795  -HSync +Vsync
3xrandr --addmode VGA-1 1368x768
4xrandr --output VGA-1 --mode 1368x768

get Modeline

1cvt 1366 768

1# 1368x768 59.88 Hz (CVT) hsync: 47.79 kHz; pclk: 85.25 MHz
2Modeline "1368x768_60.00"   85.25  1368 1440 1576 1784  768 771 781 798 -hsync +vsync

create and add mode

1# Add the resolution supported by Acer Aspire 5742 on VGA port
2xrandr --newmode "1368x768_60.00"   85.25  1368 1440 1576 1784  768 771 781 798 -hsync +vsync
3xrandr --addmode VGA-1 1368x768_60.00

1# find the monitor identifier to set the mode for
2xrandr --listmonitors

Monitors: 2
 0: +*LVDS-1 1366/344x768/194+0+0  LVDS-1
 1: +VGA-1 1024/271x768/203+1366+0  VGA-1

set output mode

1xrandr --output VGA-1 --mode 1368x768_60.00

create .xprofile

Create a ~/.xprofile file and simply add the commands for the programs you wish to start with the session

Add SSH Key to MacOS Keychain permanently

Mon, 20 Feb 2017 00:00:01 +0500

Run ssh-agent if it’s not already running

1eval "$(ssh-agent -s)"

Add SSH key to ssh-agent

1ssh-add -K ~/.ssh/id_rsa

where id_rsa is the actual filename of the key you’re adding. This should do it for OSX before Sierra.

MacOS Sierra

Create an SSH config file

1nano ~/.ssh/config

Add the following to it

1Host *
2UseKeychain yes
3AddKeysToAgent yes
4IdentityFile ~/.ssh/id_rsa

UseKeychain yes tells SSH to look in your OSX keychain for the key passphrase.
IdentityFile specifies the key you want to load. If you want to load multiple keys just add more IdentityFile entries, one per line.

Now add your key(s)

Run JNLP Files on Ubuntu

Mon, 23 Jan 2017 00:00:02 +0500

1sudo apt install icedtea-netx -y

icedtea-netx requires openjdk-8-jre and openjdk-8-jre-headless as dependencies so it’ll install JRE (Java Runtime Environment) for you as well if you don’t have that already.

JNLP is Java Network Launching Protocol
icdeatea-netx is Netx implementation of JNLP
icedtea-plugin is web browser plugin to execute Java applets. No longer available in Ubuntu (20.04)

Setting up shared network between Ubuntu and Mac using Samba

Mon, 23 Jan 2017 00:00:01 +0500

Ubuntu 16.04 LTS

Install Samba

1sudo apt install -y samba

Config

1# make a backup of original conf file
2sudo /etc/samba/smb.conf /etc/samba/smb_bak.conf
3# edit conf file and add share folders
4sudo nano /etc/samba/smb.conf

 1# SHARED FOLDERS
 2# Added by Aamnah on Fri 25 May 2018
 3
 4[Movies]
 5    comment = Movies
 6    path = /media/NAS/MOVIES/
 7    browseable = yes
 8    read only = no
 9    guest ok = yes
10    
11[TVShows]
12    comment = TV Show
13    path = "/media/NAS/TV Shows/"
14    browseable = yes
15    read only = no
16    guest ok = yes

1# restart Samba
2sudo /etc/init.d/samba restart

Create a user to use with Samba

1# create user
2sudo useradd bumblebee -m -G users
3# set password for the user you just created
4sudo passwd bumblebee

Set a password for your user in Samba

1sudo smbpasswd -a <username>

Right click on folder > Properties > Share this folder

Getting WiFi details in Linux

Thu, 15 Sep 2016 00:00:00 +0500

put wireless card in monitor mode

1sudo iwconfig wlan0 mode monitor && iwconfig

via airmon

1airmon-ng start wlan0

wlan0mon here is your wifi in monitor mode. To disable, run airmon-ng stop wlan0mon

get wifi details (BSSID)

iwlist scan
wash -i wlan0mon --ignore-fcs
airodump-ng wlan0mon

get available networks

1iwlist scanning

1airodump-ng wlan0

put wifi card in monitor mode

1airmon-ng start wlan0

Image Optimization on a Linux server

Mon, 20 Jun 2016 00:00:00 +0500

jpegoptim

You can do a test run with the -n aka --noaction flag. It will print results without taking any action

jpegoptim -n img/

opencart directories with images

image/catalog/
catalog/view/

 1#!/bin/bash
 2
 3# optimize-images.sh
 4
 5install() {
 6  # Install tools if not already installed
 7  sudo apt-get install jpegoptim optipng
 8}
 9
10
11optimize_jpeg() {
12  # jpegoptim -pqt --all-progressive *.jpeg
13  
14  # -p, --preserve, Preserve file modification times.
15  # -q, --quiet, Quiet mode.
16  # -t, --totals, Print totals after processing all files.
17  # --all-progressive, Force  all output files to be progressive.
18  
19  find -type f -name "*.jpg" -exec jpegoptim -pqtn --all-progressive {} \;
20}
21
22optimize_png() {
23  find -type f -name "*.png" -exec optipng -simulate -quiet {} \;
24  echo "Optimizing PNGs.. .. "
25}
26
27install
28optimize_jpeg
29optimize_png
30
31echo "Success: Image files have been optimized."

[modprobe, lsmod, insmod, rmmod] List, Add, Remove Kernel Modules

Sun, 17 Jan 2016 00:00:00 +0500

Building on previous lessons in this section, we will learn how to probe our kernel with the appropriate device driver and determine whether it is loaded and functioning as expected. We will also discuss how we can use the configuration of modprobe to blacklist or prevent some device drivers from loading even if the hardware is present on our system as well as why we might need to do that.

Linux Disk File Systems (ext2, ext3, Reiser, ext4)

Fri, 18 Dec 2015 00:00:00 +0500

ext2

2nd Extended File System. It was originally introduced back in 1993 and ext2 stores data in the standard hierarchial fashion used by most other file systems.

Data is stored in files, files are stored in directories, and a directory can simply contain either files or other directories.

Max file size is 2TB. An ext2 volume can be upto 4TB. File names can be upto 255 characters long and ext2 supports Linux filesystem users, groups and permissions. It also supports compression.

[Bash] Bash PATH Environment Variable

Fri, 20 Nov 2015 00:00:00 +0500

 1~ $ echo $PATH
 2/Library/Frameworks/Python.framework/Versions/3.4/bin:/usr/local/sbin:/usr/local/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/aamnah/Dropbox/todo
 3
 4~ $ cat /etc/paths
 5/usr/local/bin
 6/usr/bin
 7/bin
 8/usr/sbin
 9/sbin
10
11PATH=/usr/local/bin:$PATH # prepend a path to your current $PATH

Ubuntu

The following command adds (appends) a path to your current path:

1export PATH=$PATH:/my/custom/path

If you want your setup to execute this command every time, there are a number of places where you can put it. When you login, the following scripts will be executed in this order:

SSH Tunneling / Port Forwarding

Sun, 15 Nov 2015 00:00:01 +0500

1ssh -f -N -L 2222:vortex.myserver.com:22 user@jumphost

-f go to the background (just before running the command, so you can still type a password first). It does NOT mean force
-L local port forward, in the form local_port:destination_host:destination_port
-N don’t execute any commands at remote host, just forward the port
2222 is local port
vortex.myserver.com is remote server, the one you actually want to reach
22 is remote port
user@jumphost is the server you SSH into. The connection to vortex.myserver.com:22 is made from there, so vortex only has to be reachable from the jump host, not from you
ssh -L 2222:vortex.myserver.com:22 localhost only works if you run an SSH server on your own machine, because then localhost is the server you log into

Now connect to the local port, and you end up on vortex:

SSH Keys

Sun, 15 Nov 2015 00:00:00 +0500

Generate a key pair locally
Give the public key to the remote server
Keep the private key yourself

Generate key

1ssh-keygen -t ed25519

Previously, i used to use rsa as the type, but i have since moved on to ed25519. Ed25519 is a newer public-key algorithm which is faster (and safer) than RSA. Ed25519 public-key is also more compact, containing only 68 characters as compared to RSA 3072 that has 544 characters. Ed25519 is supported by OpenSSH so you should be good in almost all cases.

FHS, File System Architecture and Directory Structure

Thu, 12 Nov 2015 00:00:00 +0500

Filesystem Hierarchy Standard

FHS is the standard method of laying out the directory structure in Linux distributions, so that the contents follow a standard layout. That you can always depend upon certain types of files being in certain types of directories, and that they are generally consistent accross distributions.

Some systems may deviate from FHS in some areas. The current FHS is v2.3, was actually announced Jan 29th, 2004. v3 has been under development for almost 5 years. It stands to reason that some Linux file systems or dirs may have developed over the last ten years use of Linux that don’t quite fit this FHS standard.

Configuring WIFI via Command Line

Mon, 24 Aug 2015 00:00:00 +0500

The RaspberryPi Wireless WiFi Dongle Configuration guide by Farnell is THE BEST i’ve found so far.

To check if your wifi dongle is recognized

ifconfig

if you see wlan0, it confirms that raspberry pi has detected your wifi adaptor.

To scan for wifi networks

sudo iwlist wlan0 scan

Edit the `wpa_supplicant.conf` file

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

Add the following with your network details at the end of the file, below update_config=1.

Yum Transaction Check Errors & Dependencies/Package Conflicts

Mon, 19 Jan 2015 00:00:02 +0500

Transaction Check Error:
  file /etc/pki/tls/certs/ca-bundle.crt from install of openssl-0.9.8e-32.el5_11.x86_64 conflicts with file from package openssl-0.9.8e-26.el5_9.1.i686
  file /usr/share/man/man1/ca.1ssl.gz from install of openssl-0.9.8e-32.el5_11.x86_64 conflicts with file from package openssl-0.9.8e-26.el5_9.1.i686
  file /usr/share/man/man1/req.1ssl.gz from install of openssl-0.9.8e-32.el5_11.x86_64 conflicts with file from package openssl-0.9.8e-26.el5_9.1.i686
  file /usr/share/man/man1/x509.1ssl.gz from install of openssl-0.9.8e-32.el5_11.x86_64 conflicts with file from package openssl-0.9.8e-26.el5_9.1.i686

This can happen if:

package architecture is different (32-bit vs 64-bit)
package source/repo is different
you have a newer package installed while the repo you are trying to ‘update’ from has an older version
package already installed is 32-bit but 32-bit packages are excluded in /etc/yum.conf so it won’t update

This issue was resolved by adding multilib_policy=best to /etc/yum.conf.

How to install Node.js on CentOS/cPanel

Mon, 19 Jan 2015 00:00:01 +0500

Run as root on RHEL, CentOS or Fedora:

1curl -sL https://rpm.nodesource.com/setup | bash -

Then install, as root:

1yum install -y nodejs

The -y flag will automatically answer “yes” to every confirmation question, so leave it out if you want to be able to say no to something.

Optional: install build tools

To compile and install native addons from npm you may also need to install build tools:

1yum install gcc-c++ make

Editing Apache Configuration on a cPanel/CentOS Server

Mon, 19 Jan 2015 00:00:00 +0500

According to cPanel docs, it’s easier to use EasyApache for configuring and regenerating Apache. If you want the recommended way, skip this article. I’m more of a command line gal, so i’ll go ahead and detail the process of editing httpd.conf from the command line, enabling some modules, adding configurations, retaining the configuration and checking if your configuration has been preserved.

On Debian/Ubuntu it’s easier to enable a module. You run the command a2enmod followed by the name of the module and it gets enabled. Then you restart Apache by running another command sudo /etc/init.d/apache2 restart so your configurations take effect.

How to Install Git on CentOS

Sun, 18 Jan 2015 00:00:00 +0500

The Easy Way

sudo yum install git

git --version to make sure it’s installed.

Compiling from Source

Make sure you have sudo access.

Install Compilation tools

sudo yum groupinstall "Development Tools"

Instll Dependencies

CentOS 6.x

sudo yum install zlib-devel perl-ExtUtils-MakeMaker asciidoc xmlto openssl-devel

CentOS 7.x

sudo yum install gettext-devel openssl-devel perl-CPAN perl-devel zlib-devel

Fetch source files

wget https://github.com/git/git/archive/v2.2.2.tar.gz -O git.tar.gz

Check Github Release page for the latest stable version. Or install teh latest -rc (release candidate) version if you are feeling dangerous. Latest stable is recommended.

Generating an SSH Key and Copying it to Remote Server

Tue, 26 Aug 2014 00:00:05 +0500

1mkdir ~/.ssh && chmod 700 ~/.ssh
2touch ~/.ssh/authorized_keys && chmod 600 ~/.ssh/authorized_keys
3# copy key.pub to authorized_keys
4# nano /etc/ssh/sshd_config
5service ssh reload

Generate the Key (on local server)

1cd ~/.ssh && ssh-keygen -t ed25519

Ed25519 is a newer algorithm which is faster than RSA. Ed25519 is supported by OpenSSH so you should be good in almost all cases. Github recommends passing it your email with -C which is then uses as a label.

1cd ~/.ssh && ssh-keygen -t ed25519 -C "hello@example.com"

Add SSH key to macOS Keychain

1ssh-add --apple-use-keychain ~/.ssh/id_ed25519

Making Sure the Remote Server Accepts SSH Keys

view the server’s sshd_config file

Install Ruby on Ubuntu

Tue, 26 Aug 2014 00:00:04 +0500

 1# update packages
 2sudo apt-get update
 3# install curl if not already there
 4sudo apt-get install curl -y
 5# install RVM
 6\curl -L https://get.rvm.io | bash -s stable
 7# load RVM
 8source ~/.rvm/scripts/rvm
 9# install RVM dependencies
10rvm requirements
11
12# install ruby
13rvm install ruby
14# use default ruby version (latest)
15rvm use ruby --default
16# install rubygems
17rvm rubygems current
18# install Rails
19gem install rails

notes

the setup seems to be user specific

issues

rvm requirements needs to be run as root. may require a password. sudo rvm rquiremenst for some unknown reason does not seem to work.

more on rvm requirements issue

the error happens when there are broken sources in /etc/apt/sources.list or /etc/apt/sources.list.d/*.list x
the broken source list is because “Ubuntu 12.10 is not supported any more since May 2014. You either need to update to a more recent version of Ubuntu (i.e. 14.04), or find an alternative repository.” x
solution sudo apt-get update && sudo apt-get install update-manager-core && sudo do-release-upgrade x
the problem with the solution: Ubuntu can only be updated to the next version. Direct upgrades to the latest version only works LTS to LTS. In my case, the server is still on 12.10 (12.04 was LTS, the latest at the moment is 14.04 has already arrived) the best strategy at this point is to take backups and restore on a fresh install of latest version.

Command line color settings (GNU)

Tue, 26 Aug 2014 00:00:03 +0500

Coloring the `list` and `tree` command outputs (GNU)

Customizing Colors (GNU)

The format is as follows: LS_COLORS="di=01;90:ow=01;90"

The LS_COLORS environment variable is a colon : separated list of key=colour pairs. There are 2 types of key: file types and file extensions.

key	effect	color	meaning
di	01	90	color all dirs dark grey and make it bold
ow	01	90	color all other_writable (o+w) dirs dark grey and make it bold

Coloring the Mac Terminal

Tue, 26 Aug 2014 00:00:02 +0500

Adding colors to `ls` and `tree`

Enabling Colors

Edit ~/.bash_profile or ~/.profile and add the following two lines:

1export CLICOLOR=1
2export LSCOLORS=ExFxCxDxBxegedabagacad

you can use this if you are using a black background:

1export LSCOLORS=gxBxhxDxfxhxhxhxhxcxcx

LSCOLORS="ExGxBxDxCxEgEdxbxgxcxd" will emulate the default colouring on the linux ls command.

Making it permanent

You can add

1alias ls='ls -Gp'
2alias tree="tree -C"

to your ~/.bash_profile to ALWAYS get colored ls and tree output.

-G enables colorized output and the -p adds a slash after each directory. the -C turns on colorization for the tree command.

Crontab Basics

Wed, 21 May 2014 16:32:55 +0500

tl;dr

1crontab -l # List crontab entries
2crontab -e # Edit a crontab using the EDITOR specified (export EDITOR=nano)
3crontab -r # Remove a crontab
4sudo crontab -e # Edit root user’s crontab
5crontab my-crontab # add cron jobs by giving a file to crontab

If you are adding a script in any of the cron directories, it has to be executable
Use absolute paths for files, directories and executable commands
it should link to the absolute path of the executables (commands). e.g. /bin/echo instead of echo. Find out absolute paths with the which command, e.g. which echo (or consider adding PATH at the top of the crontab file)
Commands that need to be run with sudo should be added to the root user’s crontab
Have your script create a file that log success or failure, makes it easier to troubleshoot cron echo "Nightly Backup Successful: $(date)" >> /tmp/mybackup.log
Recommended is to add cron jobs to any of the cron directories (e.g. /etc/cron.d) instead of editing a user’s crontab (crontab -e)
The user adding the crons needs to be in cron.allow (if it exists)
User access is determined by /etc/cron.allow and /etc/cron.deny, if they exist. Blank /etc/cron.deny means only root is allowed access, plus everyone who’s in /etc/cron.allow. No cron.allow and cron.deny means everyone has access

Where to add your cron jobs?

There are plenty of places where you can place your cron jobs. You can

Nagios

Wed, 21 May 2014 16:31:32 +0500

Install: apt update && apt install -y nagios3
Check install: dpkg -l | grep -i nagios
Default login: nagiosadmin, g_!_o
Listing packages of nagios: dpkg -L nagios3

NOTES

aptitude is a front-end for dpkg. dpkg is the package manager.

Unix: Using pushd and popd for faster navigation

Wed, 21 May 2014 15:33:21 +0500

Unix: Using pushd and popd for faster navigation

The pushd and popd commands put directory paths onto a directory stack (pushd) and then pop them off again (popd). Using the pushd and popd commands is not unlike dropping directory “bread crumbs” and then returning in reverse order to all the places you visited.

TL;DR

pushd and popd manage a directory stack — cd with a memory. It’s LIFO: last in, first out.

Unix: Pranks that sysadmins play

Wed, 21 May 2014 15:32:18 +0500

Unix: Pranks that sysadmins play

Unix systems administrators tend to be very serious about their responsibilities – except when they’re not. And, when they’re not, the pranks that they play on each other and some of their more annoying users might surprise you.

TL;DR

A catalogue of classic sysadmin pranks that exploit command-line knowledge the victim doesn’t have.

Alias tricks

Redefine a common command to do something weird or break loudly:

Linux on Aamnah - Frontend Web Developer

Enable macOS like touchpad gestures on Ubuntu

Installation and setup

Add missing Monitor Resolution profile

tl;dr

get Modeline

create and add mode

set output mode

create .xprofile

Add SSH Key to MacOS Keychain permanently

MacOS Sierra

Run JNLP Files on Ubuntu

Setting up shared network between Ubuntu and Mac using Samba

Install Samba

Config

Create a user to use with Samba

Set a password for your user in Samba

Share a folder

Getting WiFi details in Linux

put wireless card in monitor mode

get wifi details (BSSID)

get available networks

put wifi card in monitor mode

Image Optimization on a Linux server

jpegoptim

opencart directories with images

Links

[modprobe, lsmod, insmod, rmmod] List, Add, Remove Kernel Modules

Linux Disk File Systems (ext2, ext3, Reiser, ext4)

ext2

[Bash] Bash PATH Environment Variable

Ubuntu

SSH Tunneling / Port Forwarding

SSH Keys

Generate key

FHS, File System Architecture and Directory Structure

Filesystem Hierarchy Standard

Configuring WIFI via Command Line

To check if your wifi dongle is recognized

To scan for wifi networks

Edit the wpa_supplicant.conf file

Yum Transaction Check Errors & Dependencies/Package Conflicts

How to install Node.js on CentOS/cPanel

Editing Apache Configuration on a cPanel/CentOS Server

How to Install Git on CentOS

The Easy Way

Compiling from Source

Install Compilation tools

Instll Dependencies

Fetch source files

Generating an SSH Key and Copying it to Remote Server

Generate the Key (on local server)

Add SSH key to macOS Keychain

Making Sure the Remote Server Accepts SSH Keys

Install Ruby on Ubuntu

notes

issues

more on rvm requirements issue

Links

Command line color settings (GNU)

Coloring the list and tree command outputs (GNU)

Customizing Colors (GNU)

Links:

Coloring the Mac Terminal

Adding colors to ls and tree

Enabling Colors

Making it permanent

Crontab Basics

tl;dr

Where to add your cron jobs?

Nagios

NOTES

Unix: Using pushd and popd for faster navigation

TL;DR

Unix: Pranks that sysadmins play

TL;DR

Alias tricks

Edit the `wpa_supplicant.conf` file

Coloring the `list` and `tree` command outputs (GNU)

Adding colors to `ls` and `tree`