A terminal is an environment for text input/output. Inside the terminal, one runs command-line and text mode programs (including shells).

learn more… | top users | synonyms

681
votes
5answers
157k views

What is the exact difference between a 'terminal', a 'shell', a 'tty' and a 'console'?

I think these terms almost refer to the same thing, when used loosely: terminal shell tty console What exactly does each of these terms refer to?
237
votes
3answers
138k views

How to unfreeze after accidentally pressing Ctrl-S in a terminal?

It's a situation that has happened quite often to me: after I press (with a different intention) Ctrl-S in a terminal, the interaction (input or output) with it is frozen. It's probably a kind of ...
139
votes
8answers
177k views

How to split the terminal into more than one “view”?

From vi, if you issue the command :sp, the screen splits into two "views", allowing you to edit more than one file from the same terminal. Along those same lines, is there a way to have multiple ...
135
votes
10answers
117k views

How can I close a terminal without killing the command running in it?

Sometimes I want to start a process and forget about it. If I start it from the command line, like this: redshift I can't close the terminal, or it will kill the process. Can I run a command in ...
127
votes
7answers
147k views

How to display `top` results sorted by memory usage in real time?

How can I display the top results in my terminal in real time so that the list is sorted by memory usage?
111
votes
8answers
59k views

How can I disown a running process and associate it to a new screen shell?

I have a running program on a SSH shell. I want to pause it and be able to unpause its execution when I come back. One way I thought of doing that was to transfer its ownership to a screen shell, ...
108
votes
7answers
13k views

How to kill a runaway cat?

Many times I accidentally run the cat command on files that have contents up to few thousand lines. I try to kill the cat command with Ctrl+ C or Ctrl+Z, but both only take effect after the total ...
86
votes
3answers
18k views

Watch YouTube videos in terminal

Like the title says it, I'm looking for a way to watch YouTube videos in terminal (not in a browser or another window, but right there, in any bash session). Is there a simple way to do this? I ...
78
votes
2answers
40k views

Ctrl-s hang terminal emulator?

I came across a sentence in vimdoc: Note: CTRL-S does not work on all terminals and might block further input, use CTRL-Q to get going again. and this key indeed hangs my vim. I was ...
76
votes
4answers
14k views

What is the point of Ctrl-S?

Ctrl+S stops all output to the terminal which can be restarted with Ctrl+Q. But, why does Ctrl+S exist in the first place? What problem was trying to be solved by putting that control sequence in ...
61
votes
2answers
4k views

Clear / erase a mistyped invisible password on a shell / terminal in Linux

One thing that annoys me using Linux's terminal is when I have to type a invisble password, like when you run ssh. Sometimes I mistype one or more letters and then I have to press backspace key a few ...
61
votes
7answers
4k views

How safe is it to cat an arbitrary file?

Sometimes when I cat a binary file by mistake, my terminal gets garbled up. Nothing a quick reset can't fix, but couldn't an attacker theoretically create a file that, when displayed on a terminal, ...
58
votes
4answers
184k views

How to append multiple lines to a file with bash

I am writing a bash script to look for a file if it doesn't exist then create it and append this to it: Host localhost ForwardAgent yes So "line then new line 'tab' then text" I think its a ...
58
votes
3answers
41k views

Scroll inside Screen, or Pause Output

I use screen for my command-line tasks while managing the servers where I work. I usually run small commands (mostly file-system tasks) but sometimes I run more extensive tasks (like DBA). The output ...
56
votes
2answers
135k views

List all connected SSH sessions?

I just SSH'd into root, and then SSH'd again into root on the same machine. So I have two windows open both SSH'd into root on my remote machine. From the shell, how can I see a list of these two ...
52
votes
6answers
6k views

Can I configure my shell to print STDERR and STDOUT in different colors?

I want to set my terminal up so stderr is printed in a different color than stdout; maybe red. This would make it easier to tell the two apart. Is there a way to configure this in .bashrc? If not, is ...
51
votes
4answers
74k views

How to recover a 'lost' screen session?

Somehow I managed to close a screen window without screen 'noticing' it, so the session is still flagged as attached. This prevents me from re-attaching to this session. What can I do? ...
51
votes
1answer
10k views

Kill an unresponsive ssh session without closing the terminal

Is there a way to disconnect from an SSH session that has become unresponsive without killing the whole terminal? Specifically I'm using konsole, and the machine I'm working with sometimes hangs, but ...
44
votes
3answers
21k views

How can I break away from an SSH session that has crashed?

Many times I have an SSH session that doesn't respond anymore (for example, when I lose internet connection and then reconnect). Ctrl+C, Ctrl+D, Ctrl+Z and a zillion of key presses don't have any ...
43
votes
2answers
5k views

Can a terminal emulator be as fast as TTY 1-6?

I've been trying various terminal emulators lately, from the built-in gnome-terminal, aterm, xterm, wterm, to rxvt. The test I've been doing is in this order: Open up a tmux window with 2 panes The ...
38
votes
3answers
22k views

What are pseudo terminals (pty/tty)?

This might be really basic question but I want to understand it thoroughly. What is a pseudo terminal? (tty/pty) Why do we need them? How they got introduced and what was the need for it? Are they ...
36
votes
7answers
37k views

Disable screen blanking on text console

I'm running linux clusters, mostly on SLES10. The servers are mostly blades, accessed via remote console. There is a real console in the server room, but switched off. I would like to disable the ...
36
votes
4answers
40k views

How to attach terminal to detached process?

I have detached a process from my terminal, like this: $ process & That terminal is now long closed, but process is still running and I want to send some commands to that process's stdin. Is ...
35
votes
5answers
142k views

How to find application's path from command line?

For example, I have git installed on my system. But I don't remember where I installed it, so which command is fit to find this out?
35
votes
5answers
2k views

Syntax highlighting in the terminal

Lots of programming-oriented editors will colorize source code. Is there a command that will colorize source code for viewing in the terminal? I could open a file with emacs -nw (which opens in the ...
35
votes
5answers
36k views

How to clear terminal completely?

When we use clear command or Ctrl+L in terminal, it clears terminal but we can still scroll back to view the last used commands. Is there a way to completely clear the terminal?
35
votes
3answers
97k views

What is the best text-mode browser? [closed]

I am looking for one that is updated frequently and has support for many things.
34
votes
5answers
38k views

How to scroll in a terminal using keyboard?

How can I scroll in bash using only the keyboard? If it's not possible in bash, are there any other shells that support this?
34
votes
4answers
5k views

What are the responsibilities of each Pseudo-Terminal (PTY) component (software, master side, slave side)?

I am trying to figure out how a tty works1 (the work-flow and responsibilities of each elements). I have read several interesting articles about it, but there are still some blurry areas. This is ...
34
votes
3answers
30k views

What is stored in /dev/pts files and can we open them?

According to my knowledge, /dev/pts files are created for ssh or telnet sessions.
34
votes
2answers
38k views

How to signal the end of stdin input in bash

In Bash, I learned that the ending signal can be changed by here document. But by default how can I signal the end of stdin input? I happened to find that with cat and chardet, their stdin inputs can ...
33
votes
1answer
1k views

What happens when Ctrl + Alt + F<Num> is pressed?

I am looking for an explanation of what happens in Linux when this key combination is pressed to change the current terminal. In particular, what software component intercepts this key combination and ...
32
votes
9answers
134k views

How to connect to a serial port as simple as using SSH?

Is there a way to connect to a serial terminal just as you would do with SSH? There must be a simpler way than tools such as Minicom, like this $ serial /dev/ttyS0 I know I can cat the output ...
32
votes
6answers
13k views

How to check if bash can print colors

I want to know if there's any way to check if my program can output terminal output using colors or not. Running commands like less and looking at the output from a program that outputs using ...
32
votes
2answers
13k views

Fix terminal after displaying a binary file

I'd tried command cat with an executable file: cat /bin/ls Now I can't read any word in this terminal (Linux console). How can I fix it?
31
votes
3answers
12k views

Terminal prompt not wrapping correctly

I have an issue where if I type in very long commands in bash the terminal will not render what I'm typing correctly. I'd expect that if I had a command like the following: username@someserver ...
31
votes
4answers
29k views

Dark blue color in vim or ls output in linux

I have a problem with dark-blue color in vim or ls output. Because I'm using black background color, words colored in dark-blue are almost completely invisible. How can I address this problem?
31
votes
3answers
43k views

SSH inside SSH fails with “stdin: is not a tty”

I'm trying to connect to machine one with ssh and then connect to another machine two with ssh, but I get this error. ssh user@computerone.com 'ssh otheruser@computertwo.com' stdin: is not a tty ...
31
votes
3answers
26k views

Which terminal type am I using?

I have tested this with both Ubuntu 12.04 and Debian 7. When I do echo $TERM I get xterm But if I use the dropdown menu "help" > "about" then it says gnome terminal 3.4.1.1. Does this mean I am ...
30
votes
3answers
4k views

Why is the password I entered not visible?

Below is an image of the process I took to create a user on bash in Linux. I understand that the password shouldn't be displayed for security purposes, but what I mean is, why do asterisks (or the ...
28
votes
5answers
4k views

How does clear command work?

I was recently trying to learn more about how the shell works and was looking at how the clear command works. The executable is located in /usr/bin/clear and it seems to print out a bunch of blank ...
28
votes
2answers
14k views

Output from ls has newlines but displays on a single line. Why?

I think I may be overlooking a relatively fundamental point regarding shell. Output from the ls command by default separates output with newlines, but the shell displays the output on a single line. ...
27
votes
6answers
20k views

Removing control chars (including console codes / colours) from script output

I can use the "script" command to record an interactive session at the command line. However, this includes all control characters and colour codes. I can remove control characters (like backspace) ...
27
votes
3answers
24k views

tmux, TERM and 256 colours support

Introduction My question arises from the necessity of understanding why I have now (after multiple trials) Terminal and tmux supporting 256 colours and tput colors telling me there are only 8 of ...
27
votes
7answers
11k views

Converting colored output into html

There are tools providing coloured output: dwdiff -c File1 File2 # word level diff grep --color=always # we all know this guy ... The question is: How to convert their colored output of arbitrary ...
26
votes
4answers
19k views

How to remove “You have mail” welcome message

When I open up my terminal it says "you have mail", anyone has any idea of why? I am running OS X, but since it too is based on Unix and relies on files such as bashrc, bash_profile etc. I thought ...
25
votes
2answers
97k views

Sending messages to another user

Is there any command to send messages through the Linux shell to other people on the same network? I'm using write user and then write the message itself. But there's any command that doesn't show my ...
24
votes
6answers
6k views

Using VI keys to edit shell commands in UNIX

I used to have a co-worker who was really good at UNIX. He showed me how to use Vi key bindings to edit my shell commands. He placed the command in a file that ran every time I logged in. Since ...
24
votes
2answers
4k views

disable CTRL-D window close in terminator (terminal emulator)

I am often logged in through multiple SSH sessions. To logout from my sessions, I press CTRL+d, until I am back on my local machine. However, sometimes I press once too many, and my terminal exits. ...
23
votes
7answers
30k views

How to disable line wrap in a terminal?

I need to view large logs files using a bash shell. I was using less to open the files, but since the lines are too lengthy there is some kind of line/word wrapping going on. Since the files are ...