Questions about using the command-line interface (CLI).

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177
votes
6answers
212k views

How can I recursively delete all files of a specific extension in the current directory?

How do I safely delete all files with a specific extension (e.g. .bak) from current directory and all subfolders using one command-line? Simply, I'm afraid to use rm since I used it wrong once and now ...
95
votes
6answers
118k views

How can I get a list of all repositories and PPAs from the command line into an install script?

I know how to list all packages installed on my system. But how could I get a list of all repositories and PPA's? I know I can look into /etc/apt/sources.list and /etc/apt/sources.list.d, but I'm ...
71
votes
10answers
58k views

Why do I need to type `./` before executing a program in the current directory?

While executing a C program, a.out, using the Ubuntu terminal, why do I always need to type ./ before a.out, instead of just writing a.out? Is there solution for this?
39
votes
10answers
8k views

Delete all files except files with the extension pdf in a directory

I have a directory that contains the following: x.pdf y.zip z.mp3 a.pdf I want to delete all files apart from x.pdf and a.pdf. How do I do this from the terminal? There are no subdirectories so no ...
28
votes
3answers
8k views

Where should I put my script so that I can run it by a direct command?

Where can (should) I put my (bash) script so that it can be used (forever) by terminal or by a direct command: Alt+F2? I know there is /usr/bin and /sbin & /bindirectories but when should I use ...
21
votes
2answers
31k views

How can I create a custom terminal command (to run a script)?

I'm a web developer. When I want to start working, always i'm executing some command on terminal. For example: sudo service apache2 start sudo service mysql start sublime For speed up this process, ...
20
votes
1answer
6k views

How to configure pkexec?

Reading these questions and answers: When to use pkexec vs. gksu/gksudo? Why is gksu no longer installed by default? brought me another one that will create problems for new users of that command:...
19
votes
2answers
131k views

Terminal method of formatting storage drive

I want to know how to format a storage drive from the terminal. Helpful things to provide in the answer would be often used options for commands and base knowledge that one can use to extrapolate ...
41
votes
7answers
19k views

Make a sound once process is complete

I have started a long process through a terminal. Is it possible to make the Ubuntu terminal make a sound once the process is complete? This way, I don’t need to keep checking, but will instead be ...
33
votes
6answers
197k views

How can I execute a .jar file from the terminal

I know that to execute a file, I use the . command, then the file name with a space between them. But I'm trying to execute a .jar file using the . and it does not work. I went into the properties and ...
25
votes
5answers
39k views

Environment variables when run with 'sudo'

As example to my question, my ~/.bashrc file contains this lines: export LD_LIBRARY_PATH=/opt/intel/mkl/lib/ia32:$LD_LIBRARY_PATH export LD_PRELOAD=/opt/intel/mkl/lib/ia32/libmkl_core.so so that ...
18
votes
3answers
25k views

How can I (from CLI) assign multiple IP addresses to one interface?

On my server I want to assign several IP addresses to one NIC, but without using the deprecated ifconfig or the obsolete "alias" notation (like eth0:0) in /etc/network/interfaces because in IP ...
8
votes
1answer
3k views

One line command for adding new items to com.canonical.Unity.Panel systray-whitelist

This is more of a how to use command line instruction question more than how to add items to the Unity notification panel. I have to have a one line CLI to add a new item to com.canonical.Unity.Panel ...
22
votes
5answers
12k views

In the output of 'ls -n', what does the the second column mean?

When I run: ls -n I get something like: -rwxrwxrwx 1 1000 1000 765528 2009-10-15 18:41 file1 drwxr-xr-x 10 1000 1000 4096 2010-12-07 20:50 dir1 drwxr-xr-x 3 1000 1000 4096 2010-10-24 ...
9
votes
1answer
3k views

Why is pkexec preferred over gksudo for graphical applications?

Please provide Ubuntu documentation that refutes this: https://help.ubuntu.com/community/RootSudo Why, on my fully updated 13.04 system, does pkexec not function? $ pkexec gedit somefile.txt No ...
7
votes
1answer
6k views

Ubuntu Touch using apt-get

I'm sorry if this has already been asked, I did do some searching and didn't find it. However a number of questions, I have just installed the latest Ubuntu touch, on a nexus 5, and was going to have ...
4
votes
1answer
7k views

Run simple bash script to start applications at login

I want to run a simple bash script automatically when I log in. For example #!/bin/bash echo "start spotify" gnome-terminal -e spotify --title spotify When I run this command, one gnome-terminal ...
6
votes
5answers
5k views

How do I make an entire directory executable?

I have an entire folder dedicated to python scripts. I'm tired of doing chmod on every new python script that I write. Is there a way to make every file inside my folder executable if it is a python ...
288
votes
7answers
898k views

A command to list all users? And how to add, delete, modify users?

I need a command to list all users in terminal. And how to add, delete, modify users from terminal. That could help in administrating your accounts easily by terminal.
304
votes
5answers
1.6m views

How to delete a non-empty directory in Terminal?

How do I delete the following directory? I typed: rmdir lampp This error comes up: rmdir: failed to remove `lampp': Directory not empty Is there a command to delete all the files in the ...
138
votes
1answer
95k views

Differences between /bin, /sbin, /usr/bin, /usr/sbin, /usr/local/bin, /usr/local/sbin [duplicate]

I'm running an Ubuntu Server 13.04, but I see the same on a 12.04: I have six directories with command files. These are: /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin What are the ...
63
votes
5answers
163k views

How do I save terminal output to a file?

How do I save the output of a command to a file? Is there a way without using any software? I would like to know how.
49
votes
6answers
20k views

What is the difference between ./ and sh to run a script?

I have written a simple script. When I runsh <myscriptname.sh>, i got the correct output, but when I run ./<myscriptname.sh>, I got an error. What is difference between when I do sh and ....
40
votes
3answers
376k views

How to start GUI from command line?

I've installed the following version of ubuntu om my machine. ubuntu-12.04-desktop-i386.iso But when I switch on the computer, I get command line. Ubuntu 12.04 LTS COMP-1245 tty1 Once I ...
35
votes
2answers
35k views

How do I disable the blank console “screensaver” on Ubuntu Server?

How to disable blank screensaver on Ubuntu Server? There's no desktop or X, only console (command-line interface).
32
votes
1answer
13k views

How do I pipe terminal standard output (stdout) to the clipboard?

For example, Say I want to list the contents of a folder and directly paste them into a chat window for a friend to see. I realize I could do ls > filename.txt to create a file (filename.txt) ...
22
votes
5answers
22k views

trim the terminal command prompt working directory

When using the terminal in a deep folder structure sometimes the prompt can take up most of the line. Is there any way in which I can trim the working directory? I know I can do PS1="\W >" to ...
28
votes
6answers
54k views

How can I find which desktop enviroment I am using? [duplicate]

as the title: How can I find which desktop environment I am using? I want to accomplish this using command line.
27
votes
4answers
267k views

What is a command to compile and run C++ programs?

I am new to Linux. I am using Ubuntu 11.04 and do not know how to compile and execute C++ program in it. I need to know the commands to Compile and Execute a C++ program in Linux.
25
votes
4answers
4k views

Why wouldn't the `which` command work for `cd`? I can't find the executable for `cd` either!

I tried which cd and it didn't give a path but instead returned the exit code 1 (checked with echo $?). The coreutil cd itself is working, so the executable should be there, right? I also ran a find ...
21
votes
4answers
16k views

Why is moving directories to /dev/null dangerous?

When trying to move a test_dir directory to /dev/null, I get the message mv: cannot overwrite non-directory ‘/dev/null’ with directory ‘test_dir/’ Then why do people say "Don't run the command sudo ...
6
votes
1answer
7k views

How to reinstall many removed packages at once?

I used sudo apt-get remove python command and accidently removed a bunch of packages that were required. I logged in via command line and installed ubuntu-desktop again but there are other packages ...
15
votes
0answers
12k views

Command to know my external IP address? [duplicate]

How can I get my external IP address using the Command Line?
15
votes
1answer
80k views

How to make a file executable? [duplicate]

How can I make my file so that I can double click on it, and it runs. It is a .sh script, but I also have files that say: executable (application/x-executable) in the description of what they are. ...
12
votes
3answers
12k views

Is there an easy way to log all activity that a shell script does?

Is there an easy way to log all activity that occurs from a shell script to a file? I have a script. It outputs things like echo "instructions", as well as other program output. I know the commands: ...
12
votes
4answers
151k views

How do I navigate between directories in terminal?

I am new to Linux and Ubuntu and have tried changing to folders/directories with some difficulty. Could someone explain why the following commands failed to change to the desired target folder/...
9
votes
2answers
39k views

How do I navigate to folders with spaces in their names? I get “no such file or directory” when I try

I'm completely new and lost in Ubuntu 12.04, I'm having trouble navigating to my Sublime folder which I know is in my /opt folder. Yet I've tried to no avail to navigate into it via Terminal window. ...
12
votes
3answers
4k views

What does $PATH mean?

I am trying to install something and among the steps there was this one: "Place it on your $PATH" What does this mean? What is that? I have searched both this site and on Google but everyone just ...
7
votes
3answers
2k views

How can I make a list with most used commands in terminal?

How can I make a list with most used commands in terminal? I know that this question may be unuseful for any future proposals for some of us, but even like this, the list can be useful when we don't ...
4
votes
2answers
11k views

Won't execute terminal commands

I have been using Ubuntu 12.04 for quite a while and have never had a problem come at me out of the blue like this. I'm trying to install python 3.2 on my Ubuntu system and every time I run the code ...
135
votes
5answers
107k views

Which one is better: using ; or && to execute multiple commands in one line?

In tutorials and how-to's I often see commands combined. For instance, sudo apt-get update && sudo apt-get install pyrenamer There seem to be four possible connectors: &, &&, || ...
210
votes
2answers
421k views

How do I search for available packages from the command-line?

I have successfully installed some packages using the command line 'sudo apt-get install ...' when I have known in advance that those packages are available. But how can I search for or get a list of ...
103
votes
10answers
50k views

What is the difference between Terminal, Console, Shell, and Command Line?

What is the difference between Terminal, Console, Shell, and Command Line?
136
votes
6answers
201k views

How to list all variables names and their current values?

Including not only $HOME, $PWD etc but any other you have defined.
69
votes
2answers
147k views

How to download an MP3 track from a YouTube video [duplicate]

Possible Duplicate: How to download a youtube video via terminal There are several Q&A threads that explain how to download youtube videos using the terminal. However, I would also like ...
57
votes
5answers
50k views

What is the equivalent of Windows System Properties or Device Manager?

I am new to Ubuntu. In Windows, if I want to know my system properties/configuration, I can see it by going to Control Panel and clicking on the System icon. I can also get a detailed list of the ...
50
votes
2answers
32k views

What are login and non-login shells?

It is said that settings for non login shell to go into .bashrc file and login shell settings to go into .profile file. What is really meant by login and non-login shells? Please explain without ...
59
votes
14answers
178k views

How can I create a select menu in a shell script?

I'm creating a simple bash script and I want to create a select menu in it, like this: ./script echo "Choose your option:" 1) Option 1 2) Option 2 3) Option 3 4) Quit And according to ...
91
votes
10answers
21k views

How can I tell what date Ubuntu was installed?

is there a command which will output the date that ubuntu (or any distribution) was installed?
34
votes
7answers
73k views

Mount encrypted volumes from command line?

If I have an encrypted external disk (or an internal disk that is not in fstab), I see an entry for it in Nautilus -- with an entry like "X GB Encrypted Volume". I can click on this volume, and am ...