Questions tagged [command-line]

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

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1445
votes
9answers
4.6m views

How to unzip a zip file from the Terminal?

Just downloaded a .zip file from the internet. I want to use the terminal to unzip the file. What is the correct way to do this?
1103
votes
10answers
3.4m views

How do I install a .deb file via the command line?

How do I install a .deb file via the command line?
869
votes
9answers
3.1m 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.
829
votes
5answers
2.4m views

How do I shut down or reboot from a terminal?

How can I shut down or reboot Ubuntu using terminal commands?
829
votes
7answers
2.8m views

How can I add a new user as sudoer using the command line?

After I add a user using adduser, I can't see it via System > Administration > Users and Groups unless I log out and then log in again. Is that normal? Also, can I set a newly added user as a sudoer ...
804
votes
12answers
964k views

How do I determine the total size of a directory (folder) from the command line?

Is there a simple command to display the total aggregate size (disk usage) of all files in a directory (folder)? I have tried these, and they don't do what I want: ls -l, which only displays the ...
766
votes
6answers
2.3m views

How can I copy the contents of a folder to another folder in a different directory using terminal?

I am trying to copy the contents of a folder to another folder in a different directory using terminal. Would somebody be able to provide me an example of the command line syntax required to achieve ...
731
votes
7answers
1.8m 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.
703
votes
9answers
2.2m views

How to install updates via command line?

When I log into my web server via SSH I see the information: 88 packages can be updated. 80 updates are security updates I tried apt-get update then apt-get upgrade but each time I log in I still ...
672
votes
7answers
1.4m views

Find and replace text within a file using commands

How can I find and replace specific words in a text file using command line?
642
votes
5answers
3.5m 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 directory ...
605
votes
5answers
1.4m 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 ...
574
votes
6answers
2.2m views

How do I rename a directory via the command line?

I have got the directory /home/user/oldname and I want to rename it to /home/user/newname. How can I do this in a terminal?
560
votes
8answers
1.5m views

What is the correct way to completely remove an application?

I've searched the net for such information and found different command lines, like these ones: sudo apt-get remove application sudo apt-get remove application* sudo apt-get remove --purge ...
545
votes
8answers
654k 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 ...
526
votes
9answers
1.5m views

What does “sudo apt-get update” do?

I am wondering what sudo apt-get update does? What does it update?
523
votes
6answers
2.6m views

Change folder permissions and ownership

I would like the user to have full rights on this folder (as well as all sub-directories and files in it): ~/.blabla currently owned by root. I have found numerous posts (in this forum and ...
514
votes
18answers
916k views

How do I fix my locale issue?

I am getting this message every time I do something like starting or stopping a service. perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: ...
485
votes
14answers
972k views

How to check Internet Speed via Terminal?

Instead of going to sites like speedtest.net, I want to check my current Internet speed from the terminal on Ubuntu. How can I do it?
450
votes
2answers
532k views

How do I retrieve the public key from a SSH private key?

A SSH private key as generated by ssh-keygen contains a public key part. How do I retrieve this public key from the private key? I've lost my public key and need to put the contents of this public key ...
446
votes
5answers
340k 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: &, &&, || ...
438
votes
7answers
773k views

How can I decode a base64 string from the command line?

I would like to write a bash script to decode a base64 string. For example I type decode QWxhZGRpbjpvcGVuIHNlc2FtZQ== and it prints Aladdin:open sesame and returns to the prompt. So far I have tried ...
424
votes
4answers
901k views

How do I check the version of Ubuntu I am running? [duplicate]

How can I check my current Ubuntu version through the command-line and GUI?
396
votes
12answers
584k views

How to really clear the terminal?

I can issue the clear command or press Ctrl + L to clear the current Ubuntu terminal, but this just shifts previous output upwards and if you use mouse scroll or PgUP and PgDown keys it's hard to ...
386
votes
7answers
470k views

How do I check which shell I am using?

I read that terminal is nothing but shell, and Unix provides different flavors of shells: Bourne shell (sh) C shell (csh) TC shell (tcsh) Korn shell (ksh) Bourne Again shell (bash) Questions: When ...
380
votes
6answers
371k views

How can I get octal file permissions from command line?

There is a chmod command to set file permissions, but can I get file permissions in octal mode (such as 755) from the command line?
379
votes
11answers
1.3m views

How to use “grep” command to find text including subdirectories

I want to find all files which contain a specific string of text. The grep command works, but I don't know how to use it for every directory (I can only do it for my current directory). I tried ...
373
votes
5answers
625k views

What do the different colors mean in ls?

What do the different colours in Ubuntu's ls command mean? For example, when I type the ls command in one of my folders, I get one of the files in light green, the other (which is a folder) in blue ...
367
votes
13answers
475k views

How can I suspend/hibernate from command line?

How can I suspend or hibernate my laptop using command line, without installing additional software?
365
votes
8answers
1.2m views

How to create a bootable Ubuntu USB flash drive from terminal?

Is there any way to create a bootable Ubuntu USB flash drive from the terminal without using any third-party applications like YUMI, Unetbootin, Startup Disk Creator, etc. I tried to create a ...
359
votes
16answers
2.8m views

How do I run .sh scripts?

Whenever I open a .sh file, it opens it in gedit instead of the terminal. I can't find any option similar to Right Click → Open With → Other Application... → Terminal. How do I open this file in the ...
356
votes
9answers
557k views

How to list all variables names and their current values?

How to list all variables names and their current values? Including not only $HOME, $PWD etc but any other you have defined.
342
votes
2answers
620k views

How to redirect stderr to a file [duplicate]

While using nohup to put a command to run in background some of content appear in terminal. cp: error reading ‘/mnt/tt/file.txt’: Input/output error cp: failed to extend ‘/mnt/tt/file.txt’: Input/...
341
votes
5answers
211k views

How to see the command attached to a bash alias?

Suppose I have an alias in the bash shell. Is there a simple command to print out what command the alias will run?
335
votes
9answers
311k views

How can I install just security updates from the command line?

sudo apt-get upgrade installs all updates, not just security updates. I know that I can use Update Manager to select only important security updates, but is there a way to do this from the command ...
332
votes
18answers
509k views

How to show the transfer progress and speed when copying files with cp?

Otherwise, is there any alternative command line utility that can achieve this?
323
votes
19answers
468k views

How do I check the battery's status via the terminal?

I would like a command that displays the battery status in the terminal.
318
votes
6answers
1.2m views

How to download a file from a website via terminal?

Suppose that we have a full URL of desired file e.g. http://domain.com/directory/4?action=AttachFile&do=view&target=file.tgz I would like to go without installing a new software. Is it ...
301
votes
10answers
598k views

Execute sudo without Password?

Inspired by this question.... I am the sole person using my system with 12.04. Every time I issue a sudo command; the system asks for the user password (which is good in its own way). However I was ...
300
votes
9answers
1.1m views

How to remove all files from a directory?

The closest I've gotten is # rm /path/to/directory/*.* but that doesn't work for files that don't have an extension...
291
votes
2answers
214k views

Differences between /bin, /sbin, /usr/bin, /usr/sbin, /usr/local/bin, /usr/local/sbin

I have six directories with command files. These are /bin, /sbin, /usr/bin, /usr/sbin, /usr/local/bin and /usr/local/sbin. What are the differences between these? If I'm writing my own scripts, where ...
289
votes
5answers
264k views

Why did the command “:(){ :|: & };:” make my system lag so badly I had to reboot?

DANGER! Do not run this command to 'test' it unless you are prepared for a crash and/or force-rebooting your system. I was in my Virtualbox running 12.04 trying to compile an app, and while ...
279
votes
2answers
733k views

How do I use variables in a sed command?

I tried the following code to replace QQ with ZZ, but it doesn't do what I want: var1=QQ sed -i 's/$var1/ZZ/g' $file However, this code does what I want: sed -i 's/QQ/ZZ/g' $file How do I use ...
277
votes
3answers
577k views

How to download an MP3 track from a YouTube video

There are several Q&A threads that explain how to download youtube videos using the terminal. However, I would also like to learn how to extract the video's soundtracks as MP3 files--also using ...
267
votes
6answers
443k views

How to see time stamps in bash history?

Is there any way I can see at what time the commands were executed from the bash history? We can see the order but is there any way I can get the time also? Bottom-Line: Execution time in the Bash ...
265
votes
9answers
75k views

How can I tell, from the command line, whether the machine requires a reboot?

When you install certain updates (e.g. a new kernel) in Ubuntu Desktop, you get an indication that a reboot is required (in Lucid, the logout icon turns red). How can I check, from the command line, ...
264
votes
8answers
454k views

How to select video quality from youtube-dl?

I have installed youtube-dl in my 14.04. I can download video by following command, $ youtube-dl [youtube-link] But I want to know how to select available pixel quality of youtube video(i.e 1080p, ...
260
votes
2answers
350k views

'sudo su -' vs 'sudo -i' vs 'sudo /bin/bash' - when does it matter which is used, or does it matter at all?

When I'm doing something that requires root be typed in dozens of times in a row, I prefer to switch my session to a root session. In the various tutorials and instructions I have used on the Internet,...
259
votes
8answers
764k views

Command-line to list DNS servers used by my system

Is there a command to list dns servers used by my system? I tried $ cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE ...
258
votes
9answers
1.1m views

How do I move all files from one folder to another using the command line?

I would like to know how could I move all files from a folder to another folder with a command line. Let's say I'm in my Downloads folder and there are a 100 files that I would like to move to my ...