Maythux's questions

I want make an animated .gif from an .mp4 video. I would prefer to do it from the command line, so please only list command line tools.

I want make a .gif animated picture from a given set of .jpg pictures.

I would prefer to do it from the command line, so command line tools would be very welcome.

How to get the group ID GID giving the group name.

The output would be for example:

Group adm with GID=4

There are two forms of redirection the standard output and standard error into standard output. But which one is better? and why the &> is considered the perfect?

I can't find what is the differences so that many tutorials and even bash manual state that &> is better!

So Why shall I use &> and not 2>&1

Mainly using bash shell

EDIT: Thanks for commentors

Only >& works in csh or tcsh

In ksh only 2>&1 works.

dash use >file 2>&1 redirection only

Then which one to use to ensure my script is compatible with other systems whatever the used shells are!

I want to crop an image using command line tools only indicating pixels to crop for the four directions (the same way we can crop in LibreOffice)

For example:

crop image.jpg -top 5px -bottom 7px -right 14px -left 3px

Is there such a tool (not GUI)?

Here is the situation.

I have a directory which contains many files with different extensions. I want to delete all files except one with a specific name.

This could be easily done using the GUI by selecting all and pressing ctrl and deselecting the file in question.

That is exactly what I want to, but how can I do it from the command line?

For example: dirA contains the following files:

a.txt
b.txt
c.php
d.html
a.db
b.db
e.html

I want to delete all files keeping only the file named a.txt.

What is the default PAGER used by man pages.

I,e what is the program runs the man pages?

It look some like more or less. I'm sure it's not more since more doesn't support reverse backward.

What is the group "adm" and for what it's use? and what are the differences form the group "admin"?

In order to search for a process you can use ps with grep.

For example to search for firefox

ps aux | grep firefox

How to get the same answer without using grep?

I want a command to list all users who have root privileges i.e. sudo ?

Suppose I'm a sudoer user. How could I know all other sudoer users?

The scenario:

In a bash script, I have to check if a password given by a user is a valid user password.

I.e suppose I have a user A with password PA.. In the script I asked user A to enter his password, So how to check if the string entered is really his password?...

What is the command that can be used to draw the directory tree inside the terminal emulator?

Internet connection is working.

apt-get is working.

Trying to add ppa:cooperjona/lightread but an error has raised:

Cannot add PPA 'ppa:cooperjona/lightread' . Please check that the PPA name or format is correct.

I supposed there is an error in writing or in the PPA.

I tried also the 'ppa:tombeckmann/ppa' but with same error.

Is there a way to search and then download from YouTube, with the situation that I only need to download the audio only, not the video.

How to mount a remote directory using SSH to be available same as if it is a local directory?

How to clone a harddisk to a smaller sized one.

1. Clonezilla is great but it doesn't support such functionality.
2. Also dd and PartImage don't support this demand.
3. rsync will not copy the MBR since an MBR is not a file.

I need to clone a HDD not to take a backup, so rsync is not an acceptable answer.

Any suggestions?

How can I list all MAC addresses and their associated IP addresses of the machines connected to my local network (LAN)?

I have many Virtual box machines in my Ubuntu12.04, each time i shutdown or reboot i have to start them one by one.

I wanna a help in writing script for automatically autostart the VBox machines when booting.

How can get the BIOS version of my motherboard?

The command dmidecode gives you some information about the BIOS, but I can't find what I need...

I tried dmidecode command before asking and I didn't find what I needed - I want only the BIOS version and nothing else in the output.

How do I disable switching to virtual terminals (TTYs) using(Ctrl+Alt+F1...F6) in Ubuntu?