A terminal is an environment for text input/output. Inside the terminal, one runs command-line and text mode programs (including shells).
232
votes
4answers
41k 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 do each of these terms refer to?
45
votes
2answers
16k 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 ...
42
votes
2answers
1k 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 ...
34
votes
6answers
24k 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 ...
32
votes
5answers
1k 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, ...
29
votes
4answers
13k 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 ...
24
votes
1answer
429 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 ...
23
votes
2answers
928 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 ...
23
votes
6answers
2k views
Is it possible to configure Bash so that STDERR can be a different color than STDOUT?
I'd like to set up my terminal to have STDOUT print regularly, but have STDERR print out in a different color, namely red, so I can tell the difference between the two, ie:
STDOUT: HELLO WORLD
...
22
votes
1answer
3k 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 ...
19
votes
3answers
5k 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 ...
15
votes
6answers
1k views
Using VI 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 to edit my shell commands.
He placed the command in a file that ran every time I logged in.
Since then, I've ...
15
votes
2answers
3k 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.
...
15
votes
1answer
313 views
How does “man” restore the screen when I quit the program?
If I open a man page of a program like cat or ls, it prints (may not be the appropriate word) the contents of the man page and when I press q, it shows the screen just like before invoking the man ...
15
votes
4answers
1k views
What happens to the output of a process that has been disowned and lost its terminal?
If I close the virtual terminal, where some process was started, does the output just go straight to /dev/null, or can it pollute memory somehow?
Can I anyhow grab the output to continue reading it at ...
14
votes
3answers
5k 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 ...
14
votes
1answer
1k views
Is it possible to have vim key bindings in terminal?
I'm getting used to vim bindings (like pressing w to go to word, dw to delete a word, and such) and it's modes (insert, normal, visual), and, out of curiosity would like to know: is there some kind of ...
13
votes
5answers
4k views
How can I close a terminal without killing its children (without running `screen` first)?
sometimes I run an app in the gnome-terminal, but then I suddenly have to restart gnome or something. I guess the answer to the question is also useful then I want to disconnect from SSH where ...
13
votes
5answers
2k views
Best way to use a shell with Cygwin in Windows 7
I installed Cygwin, to be disappointed that bash by default runs within "cmd.exe". I googled around and found Console2. It's not a particularly well-designed application, as doing adjustments is ...
13
votes
1answer
3k views
GNU Screen: new window name change
I can change the name of a window with Ctrl-a Shift-a. Instead of editing several window names by hand, is there a way to have them automatically named after the current directory?
12
votes
4answers
736 views
How can I create an alias for a command that includes a space?
Most of my my aliases are of this form: alias p='pwd'
I want to alias git commit so that it does git commit -v
But trying to create an alias with a space gives an error:
$ alias 'git commit'='git ...
12
votes
3answers
3k 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
...
12
votes
4answers
2k views
Why do some commands 'hang' the terminal until they've finished?
Sometimes you run a program from the terminal, say, lxpanel†. The terminal won't drop you back to the prompt, it'll hang. You can press Ctrl+C to get back to the prompt, but that will kill ...
12
votes
3answers
255 views
How to redirect whatever I enter in terminal to file
I am a novice just learning Fedora 13. I just wanted to know if its possible to redirect whatever I type in the terminal to a file, so that I would be able to see from the file, that a particular ...
12
votes
6answers
4k 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 ...
12
votes
2answers
511 views
Can I configure bash to execute “clear” before every command typed in the console?
I would like to configure bash to execute clear command every time I type some command in the terminal (before executing my command). How can I do that?
I'm using Debian Linux.
11
votes
8answers
893 views
Is screen useful?
When I need to open different processes or terminals that I need to check, I just open a new tab in my terminal and use different workspaces in my machine to keep everything organized.
I do some web ...
11
votes
6answers
21k 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 ...
11
votes
3answers
3k 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) ...
11
votes
3answers
775 views
How to know the “level” of shells I am in?
If I open a terminal like xterm I will have a shell. Then if I use ssh or zsh I will have another "level" of shell. Is there a way to know how many times I have to Ctrl+D or type exit to exit all of ...
11
votes
1answer
703 views
Ctrl-C does not work with pppd non-detached session
I have a Mini2440 ARM Board, and I have put a base Debian 6.0 system on it using multistrap.
I have used tmux to run several processes in defferent windows from /etc/rc.local. I connect to the board ...
10
votes
4answers
760 views
How did they manage to drive a Unix computer before mice and copy & paste?
Since Unix is 40 years old, Unix is older than the invention of the computer mouse. (actually only 3 years if Unix is from 1969 and the mouse from 1972) How in the world did a new user do anything ...
10
votes
1answer
1k views
What protocol/standard is used by terminals?
I was wondering how the "GUI" of a command line application is communicated over a network. Most of the time, it's quite simple (plain text / input) but sometimes it's more complex (aptitude).
Is it ...
10
votes
3answers
5k 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 ...
10
votes
3answers
2k views
Telnet send Ctrl-C
I use telnet to connect to a terminal server, which proxies the traffic to a RS-232 port.
Unfortunately when using some of the devices it is not possible to send the ctrl-C character (0x03). Instead ...
10
votes
1answer
424 views
Why don't Linux terminal emulators support full colors?
I just upgraded my gnome-terminal to use 256 colors, yet I am a bit puzzled on the reason why a terminal emulator can't support the full palette any modern desktop environment provides. I guess ...
9
votes
3answers
1k views
Is there a way to lock command line?
For example, in X session, I can use Ctrl-Alt-L to lock the screen, so it would ask for password to unlock and prevent somebody from messing with mine computer.
But if I have an open terminal session ...
9
votes
3answers
736 views
Is it safe to close shell just by clicking “X” or using “ctrl+d”?
Is it safe to close shell just by clicking "X" or using "ctrl+d" while logged in as root with su or is it safer to close it by typing "exit"? Is there any difference (security-wise) at all or is it ...
9
votes
3answers
1k views
Why don't my arrow keys work in sh?
I recently installed Ubuntu and when I run sh on the Terminal my arrow keys don't work so I can't go through my call history or edit whatever I'm typing. It just comes out as weird characters like ...
9
votes
2answers
146 views
What are the characters printed when Alt+Arrow keys are pressed?
When I press AltUp, A printed to terminal screen. Same thing happened when I pressed AltDown but B is printed instead.
Other characters that I realized;
AltLeft = D and AltRight = C
What is the ...
9
votes
3answers
4k views
Can a Gnome Terminal profile use UTF-8 by default?
I am on an Ubuntu (I think) system. I don't have root, so I can't change the locale. I want to make my default terminal profile use UTF-8 by default. There should be a way to do this, either in the ...
8
votes
4answers
554 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?
8
votes
4answers
3k 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 ...
8
votes
3answers
213 views
How can my script know when I'm in a virtual console vs. an xterm?
A few of my scripts (keymap changing, public key adding) need to act differently when in a virtual console vs. in an xterm. What's the real code for
#!/bin/ksh
if [[ in_a_virtual_console ]]; then
...
8
votes
3answers
353 views
How to fix a terminal after a binary file has been dumped inside it?
After having played with curl, a binary file has been dumped inside my terminal. For example, the horizontal lines: ─ I use to format my prompt are replaced by 'q', and it can be much worse.
Why ...
8
votes
2answers
306 views
Dynamically reformatting man pages on terminal dimension changes
One common workflow of mine is to open a manual page in a terminal, then another terminal in which to test things. The man page is formatted to the initial dimensions of the first terminal. When I now ...
8
votes
2answers
831 views
Clearing GNU Screen after full-screen application
When working at a normal xterm (not sure about a "real" terminal), when a full-screen program such as man or vim is closed, it disappears, leaving your screen so you can see your prompt, and previous ...
8
votes
1answer
8k 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?
...
8
votes
3answers
837 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 ...
8
votes
6answers
299 views
Is there a terminal app that allows filenames to be clickable?
Is there a terminal emulator (extension or app) that does link resolution for local paths?
In particular when I see things like:
...
