A shell is software that lets users interact with the operating system, usually by typing at a command-line.

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184
votes
14answers
172k views

How do I detach a process from Terminal, entirely?

I use Tilda (drop-down terminal) on Ubuntu as my "command central" - pretty much the way others might use GNOME Do, Quicksilver or Launchy. However, I'm struggling with how to completely detach a ...
121
votes
5answers
47k views

What is the difference between shell, console, and terminal?

I'm confused with the terminology. What is the difference between shell, console, and terminal?
234
votes
27answers
131k views

How to execute a command whenever a file changes?

I want a quick and simple way to execute a command whenever a file changes. I want something very simple, something I will leave running on a terminal and close it whenever I'm finished working with ...
7
votes
2answers
416 views

How to correct the unrecognizable code in my debian?

After running programs that output unrecognizable code, the whole shell would be full of unrecognizable code. How can I correct this?
253
votes
9answers
226k views

What does 'source' do?

$ whatis source source: nothing appropriate. $ man source No manual entry for source $ source bash: source: filename argument required source: usage: source filename [arguments] It exists, and it is ...
197
votes
12answers
40k views

How can I change to the previous directory instead of going up?

I currently spend a lot of my working hours moving back and forth between two paths which are very far down the tree and divert from each other at root. It strikes me that my life would be a lot ...
22
votes
3answers
11k views

Screen a running process

Sometimes I forget to run a program under a screen session and can't stop it in the middle, and I know it's going to take long. Is there a way to screen an already running process without restarting ...
19
votes
3answers
25k views

How do I fork a process that doesn't die when shell exits?

If I run emacs from the shell: $ emacs foo & and then kill that shell, emacs dies. How can I run a command so that it will not die when the shell dies? I found references to nohup, but that ...
6
votes
6answers
26k views

Accidentally deleted the Downloads folder, a windows “Special Folder”, how to restore?

I deleted the Downloads folder in my Windows 7 home directory (which I had moved and renamed to incoming) I was able to restore the folder from a backup, this restores the contents as well as Desktop....
90
votes
7answers
95k views

What to do when Ctrl + C can't kill a process?

Ctrl + C doesn't always work to kill the current process (for instance, if that process is busy in certain network operations). In that case, you just see "^C" by your cursor and can't do much else. ...
29
votes
7answers
104k views

How do I run the Windows 7 Explorer shell with Administrator Privileges by default?

The Windows 7 shell (Explorer) can be made to run with Administrator privileges by this manual process: Kill Explorer shell by holding down Shift+Ctrl, right-clicking the Shut down button in the ...
21
votes
3answers
7k views

Use GNU screen as login “shell”

What's the best way to have screen automatically run when you open a new shell, whether by login, xterm, or anything else? I see the most common recommendation is to put exec screen in your regular ...
128
votes
13answers
82k views

How to reliably keep an SSH tunnel open?

I use an SSH tunnel from work to go around various idotic firewalls (it's ok with my boss :)). The problem is, after a while the ssh connection usually hangs, and the tunnel is broken. If I could at ...
108
votes
8answers
66k views

Reload a Linux user's group assignments without logging out

When assigning a user's secondary group list using: # usermod -G <grouplist> <user> is it possible to force this group assignment to take effect without logging out all running sessions?...
112
votes
3answers
109k views

How do I change my default shell on a AWS instance?

I want to change my shell from the default bash shell to zsh on my Amazon EC2 instances. How do I go about doing it? Thanks!
67
votes
4answers
107k views

How to make new file permission inherit from the parent directory?

I have a directory called data. Then I am running a script under the user id 'robot'. robot writes to the data directory and update files inside. The idea is data is open for both me and robot to ...
80
votes
2answers
14k views

Case insensitive tab completion in Bash

Is there any way to make Bash tab complete case insensitively? $ bash --version GNU bash, version 3.2.48(1)-release (x86_64-apple-darwin10.0) Copyright (C) 2007 Free Software Foundation, Inc. I am ...
66
votes
10answers
116k views

sudo with password in one command line?

On busy days, I'd like to run $ ./configure && make && sudo make install && halt on the night and go to bed, hoping the application would automatically be installed. But ...
58
votes
3answers
32k views

scp between two remote hosts from my (third) pc

I have two remote hosts. host1-> 10.3.0.1 host2-> 10.3.0.2 Both run an ssh server. The ssh server listens on port 22 in host1 and on port 6969 in host2. Now, using my local machine, I need to copy ...
11
votes
1answer
3k views

How do I make OS X set the terminal title back to the original title when coming back from ssh?

Starting on OS X, I ssh into foo (a Linux box). My terminal title changes to foo. I then ssh into bar (another Linux box). My terminal title changes to bar. I log out of bar. My terminal title ...
17
votes
3answers
7k views

How can I do Ctrl-Z and bg in one keypress to make process continue in background?

I follow this pattern of suspending the task and then letting it to continue too often with the Ctrl-Z bg sequence. I was wondering is there any way to compress that to single keypress? My shell is ...
7
votes
3answers
39k views

How can I disable the CTRL-ALT-DEL key combination completely on XP/Vista/7?

I have been googling extensively to figure this out, and nobody seems to be able to give a direct answer. Let me start by saying that I'm NOT talking about requiring CTRL-ALT-DEL to enter logon ...
13
votes
2answers
11k views

http get from the shell in Mac OS X

I'd like to download a link like: http://example.org/file.mp3 Now, I'm enough of a shell junkie to know what SCP does, but that's about where my geek-dom ends. So is there a shell program that lets ...
1435
votes
7answers
152k views

How do I make a machine “blank screen” for a period of time (as a penalty) if certain noise levels are reached?

My kids (4 and 5) yell a lot when playing games on the computer. I found an effective cure for this. When I hear loud noises, I ssh into the game computer and do: chvt 3; sleep 15; chvt 7 This ...
159
votes
7answers
64k views

Scroll shell output with mouse in tmux

Mouse scrolling doesn't work in tmux the way it works when I run shell without tmux (in Gnome Terminal). It seems tmux sends mouse scroll events as if I pressed Up/Down keys. But I want it to scroll ...
27
votes
6answers
8k views

What zsh features do you use? [closed]

I do a lot of work in the terminal so I have learned a lot about my shell of choice, zsh. What features of zsh do you use to make yourself that much more productive at work? One of my favorites is ...
47
votes
4answers
71k views

What does “2>&1” do in command line?

I know that the > sign is used for output redirection in the command line, but I'm having trouble finding something that explains the use of 2>&1 in the command line. For example: curl ...
45
votes
4answers
35k views

Byobu vs. GNU Screen vs. tmux — usefulness and transferability of skills [closed]

So far I have used Konsole to manage multiple shell sessions but I haven't tried Byobu, GNU Screen, and tmux, which offer better support for multiple shells. They all share one main feature, which is ...
45
votes
4answers
16k views

What is the origin of the UNIX $ (dollar) prompt?

The UNIX prompt uses a $ symbol to indicate that your input is expected. I was wondering why this symbol was chosen—if there is a reason. Dollar just seems a little unexpected. A > symbol would ...
15
votes
4answers
3k views

A command before every bash command

Does anyone know a mean of putting a 'time' command before every command in a bash session?
38
votes
7answers
43k views

How can I do a recursive find and replace from the command line?

Using a shell like bash or zshell, how can I do a recursive 'find and replace'? In other words, I want to replace every occurrence of 'foo' with 'bar' in all files in this directory and its ...
38
votes
4answers
3k views

Difference between “a=b” and “export a=b” in bash

What's the difference between: a=b and export a=b In bash? I understand that they both define environment variables, but I don't fully understand the difference.
44
votes
1answer
6k views

chain Fish commands via `&&` or `||`

In Bash/ZSH and other shells, I am used to using && and ||. Is there any equivalent in Fish?
21
votes
5answers
3k views

Finding the definition of a bash function

I work in an environment that has a lot of legacy shell script magic lying around. One thing used heavy from the command line are bash functions that get sourced from some file included from some ...
16
votes
9answers
14k views

Command aliases in Command Prompt?

How can I make command aliases in Windows' Command Prompt like I would with bash? I found out about doskey in a forum thread, so I can do something like: doskey ls=dir /b ...and now the command ls ...
18
votes
1answer
4k views

Why do we have login, non-login, interactive, and non-interactive bash shells?

So the bash man pages explain what login and interactive shells are: A login shell is one whose first character of argument zero is a -, or one started with the --login option. An ...
18
votes
7answers
9k views

How to retrieve the absolute path of an arbitrary file from the OS X

I'm looking for a simple command that can be used within Bash to find the absolute and canonicalized path to a file on an OS X (similar to `readlink -f' under Linux). The following sample bash ...
31
votes
4answers
18k views

Setting environment variable for just one command in Windows cmd.exe

In Bash, I can do EDITOR=vim command and command will be run with EDITOR set to vim, but this won't affect the value of EDITOR in the shell itself. Is it possible to do this in cmd.exe?
7
votes
1answer
4k views

Shell Shortcuts in Windows OS

to open send to folder in windows 7, we type shell:sendto and to open apps folder in windows 8, we type shell:appsfolder first of all, i would like to know what is this syntax known as (shell: ...
9
votes
3answers
8k views

How do I set my shell in Mac OS X?

I know I can set "Shells open with" in the Terminal preferences, but I'm curious if there's any system-wide way of setting this (similar to updating /etc/passwd in some Unixes).
27
votes
4answers
15k views

How do I change a users default shell in OSX?

What is the correct OSX way of changing a users default shell? When I googled for it I found several references to an application called NetInfo Manager but I couldn't find it on my system. There were ...
8
votes
2answers
619 views

Can I keep . and .. out of .* expansion?

I often find it annoying (or worse) when I type command .* in bash and the command applies to the parent directory and current directory. Is there some shell option or other configuration I can ...
17
votes
9answers
51k views

Opening Explorer shell with admin privileges on XP (with IE7 installed)

I used to demote my user account so that it had no admin priveleges and used a 'sudo-like' trick where you create a shortcut to IE6 and enabled the 'Run with different credentials' option to open a ...
12
votes
7answers
9k views

Best practices to alias the rm command and make it safer

Some time ago I erroneously deleted my home folder because I ran a rm -rf * on the wrong terminal, whose working directory was the home folder! I wish I had an alias for the rm command, but it was ...
8
votes
2answers
904 views

How do I delete a file named “-p” from bash?

How do I delete a file named -p in bash? Trying rm "-p" complains that -p is not a valid argument.
8
votes
10answers
60k views

How to shut down a computer having a particular IP address?

If we have a collection of Windows and Linux computers on a LAN, is it possible to shutdown a computer having a specific IP address, using the Linux shell? Assume that I do not have ssh or telnet ...
7
votes
2answers
11k views

Feeding contents of a text file as command to telnet

With the command telnet docs.python.org 80, I can do a manual HTTP request to http://docs.python.org/2/license.html, by typing the actual request. Now, instead of typing it in live, I'd like to feed ...
2
votes
1answer
153 views

Incorrect output of history command of ssh. How to read the timestamp info correctly

I set the HISTTIMEFORMAT variable to store the timestamp info .bash_history file. I am able to display the history properly if I use interactive shell. But, when I run history command to display ...
2
votes
1answer
313 views

Execute commands using sudo in remote server after logging into PuTTY through batch file

I need to login into remote server daily and perform same set of tasks. I am using Windows platform and the remote server is Unix. I use PuTTY to login to remote server. To reduce the manual work, I ...
1
vote
2answers
271 views

How to make Zsh not store failed command

Problem I'm using oh-my-zsh and Antigen to manage my Zsh. Sometimes I will accidentally enter a wrong/failed command into Zsh and it is very annoying when the zsh-autosuggestions plugin throws up ...