Bash is the shell used in Ubuntu's command-line interface.

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35
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1answer
6k views

What's the difference between set, export and env and when should I use each?

Every so often I'll bash out a bash script and it strikes me there are a few ways of setting a variable: key=value env key=value export key=value When you're inside a script or a single command ...
29
votes
3answers
101k views

'chmod u+x' versus 'chmod +x'

What is the difference between chmod u+x and just chmod +x? I have seen a ton of tutorials that say to use u+x to make scripts executable. However, the u is not mentioned in the chmod help or ...
28
votes
3answers
6k views

Find directories that DON'T contain a file

Yes, I'm sorting out my music. I've got everything arranged beautifully in the following mantra: /Artist/Album/Track - Artist - Title.ext and if one exists, the cover sits in ...
11
votes
3answers
19k 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 ...
23
votes
3answers
17k views

Bash history handling with multiple terminals

I use mainly Terminator, and it's usually opened with 3 split terminal windows. I also use Gnome terminal for various reasons. I'm wondering how is bash history handled in this case as I sometimes ...
35
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6answers
7k views

Is there a difference between the '&&' and ';' symbols in a standard BASH terminal?

They seem to both signal BASH to commence with another command following the symbols but is there a distinct difference?
20
votes
8answers
54k views

How to remove all files and subdirectories in a directory WITHOUT deleting the directory in bash?

Is there a command to remove all files and subdirectories in a directory WITHOUT deleting the directory? For example if I have directory "dontDeleteMe" with subdirectories "1", "2", "3" and each ...
19
votes
3answers
13k views

Changing colors for user, host, directory information in terminal command prompt

Is it possible to change the colors in the command prompt for the user@computer, as well as the the current directory and command parts of the prompt display? I've already seen something like this ...
19
votes
4answers
7k views

Bash auto complete for environment variables [closed]

The bash autocomplete feature does not seem to work with environment variables in 11.04. The current behavior is indicated below export SCRIPT=/home/user/script cd $SCRIPT/<tab> results in a ...
10
votes
6answers
16k views

How to log all Bash commands by all users on a server?

Our small company runs an Ubuntu Server 11.10, to which a couple of people have SSH access. The actual terminals are sometimes used, too. How can we locally log all Bash commands run, along with user ...
19
votes
3answers
1k views

iPython Like Command History For Shell

For those of you who don't do python programming on ubuntu, ipython is a python shell on steroids, but it has this amazing feature that it not only autcompletes based on known names (i.e. the same way ...
16
votes
5answers
14k views

How can I get mv (or the * wildcard) to move hidden files?

I am migrating my home directory from an old system to a new one, and the tarball I made contains everything, including hidden files like .bashrc. However, when I move the contents of the unpacked ...
13
votes
1answer
550 views

Opening a file from terminal only by typing its name

I know that xdg-open will open from terminal a file in the user's preferred application like this: xdg-open filename But I wonder how can I open a file from the current directory in its default ...
12
votes
2answers
15k views

Configure gnome-terminal to start bash as a login shell, doesn't read .bashrc

I'm trying to integrate RVM with gnome-terminal. Per default, gnome-terminal does not start bash as a login shell. I enabled run command as a login shell as suggested in this answer about the same ...
15
votes
4answers
13k views

How do I set up an email alert when a ssh login is successful?

Does anyone have a bash script that will email or notify someone in the case of a successful login to a ssh server? I want to be notified if anyone logs into my personal box. I'm using Ubuntu 12.04 ...
13
votes
4answers
6k views

What does /dev/null mean in a shell script?

I've started learning bash scripting by using this guide: http://www.tldp.org/LDP/abs/abs-guide.pdf However I got stuck at the first script: cd /var/log cat /dev/null > messages cat /dev/null ...
26
votes
5answers
4k views

Removing folder named ~

This is the output of ls -l ls -l total 53484 drwxr-xr-x 3 root root 4096 2011-02-10 05:59 ~ -rw-r--r-- 1 root root 54313810 2011-02-13 05:09 jobs.jar -rw-r--r-- 1 root root 384035 2011-02-15 ...
18
votes
3answers
489 views

What is the $BASH_COMMAND variable good for?

According to the Bash manual, the environment variable BASH_COMMAND contains The command currently being executed or about to be executed, unless the shell is executing a command as the result of ...
13
votes
2answers
4k views

How can a script detect a user's idle time?

I want to check, inside a bash script (*), how long the user of a X session has been idle. The user himself does not have to be using bash, but just X. If the user just moved the mouse, for example, ...
10
votes
3answers
17k views

How to escape file path in SED?

I would like to replace $fileWithPath in $file, however this not works because (I think) path is not escaped. how to escape it? sed -i 's/${fileWithPath}/HAHA/g' $file
10
votes
4answers
31k views

sudo: source: command not found

I've been updating some of the default profile for bash, and saw from the tutorials I was following that I could reload the new profile with the new environment settings by using: source ...
8
votes
4answers
8k views

How do I check virtualbox version from CLI

I am writing a Bash script to store the version number of Virtualbox, but cannot succeed. My Script is: #!/bin/bash installed_virtualbox=$(virtualbox --version) # --version this is what I want to ...
8
votes
1answer
57k views

configure: error: C compiler cannot create executables

I was trying to install rvm using \curl -L https://get.rvm.io | bash -s stable --ruby --autolibs=enable --auto-dotfiles. It worked fine until I got a configure error: Error running './configure ...
5
votes
2answers
12k views

What does outputting to /dev/null accomplish in bash scripts?

Oftentimes I run into small bash scripts that use this sort of syntax in if statements: "some command" > /dev/null 2>&1 What is the purpose of outputting to /dev/null like that, and what does ...
3
votes
2answers
11k views

Using up arrow to run previous command

What setup do I need to use up-arrow to run previous command? With Mac, I can use up-arrow to rerun the command that I just run, but it doesn't seem to work with my bash shell. I use 8.04 (I can't ...
0
votes
2answers
6k views

Change the terminal prompt [duplicate]

This can be really trivial,but it helps in ways of making it more comfortable while coding and sending commands to terminal. My terminal source/bash/root name(my apologies, I dunno which is the right ...
19
votes
2answers
825 views

Why does it take so long for Ubuntu to say “command not found”

For some reason, with my setup, it can take Ubuntu several seconds to respond with "command not found" when I accidentally typo a command. Why does it take so long? Is there any way to shorten the ...
18
votes
3answers
4k views

What does “${debian_chroot:+($debian_chroot)}” do in my terminal prompt?

In my terminal prompt definition in my .bashrc file, among other things, I have this snippet of code: ${debian_chroot:+($debian_chroot)} What does this do, and do I need it?
14
votes
2answers
6k views

What has 'rm -r ~' done to my home directory?

gedit creates hidden backup files ending with '~'. I wanted to do a recursive cleanup of my directory tree. The command rm *~ will delete all local files ending with '~' I thought rm -r *~ . would ...
13
votes
7answers
4k views

Auto complete for often used command line commands?

For some projects I often type in a couple commands, like for example: cd an/extremely/long/path/in/which/I/have/some/kinda/project and ./runmyproject --with some --command line --options set ...
12
votes
2answers
8k views

Split a large file into smaller files and then integrate them to get the original file

How do I split a 7GB (movie) file into smaller files of (say) 1GB, and then (in another Ubuntu computer) integrate them to get the original file (using just bash commands)?
9
votes
7answers
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How do I sort by human readable sizes numerically?

for example I have command that shows how much space folder takes du folder | sort -n it works great, however I would like to have human readable form du -h folder however if I do that than I ...
9
votes
1answer
3k views

Why does /bin/sh point to /bin/dash and not /bin/bash?

As far as I understand bash is the default shell in Ubuntu, so why does /bin/sh point to /bin/dash?
8
votes
3answers
15k views

I can't find .bash_profile

I am trying to learn how to tweak my shell in the file but can't seems to find the file in my home directory or in /etc/profile. Is there any other file I need to search for, or am I expected to ...
7
votes
3answers
5k views

How do I install utorrent by hand?

So I'm new to Ubuntu, in fact I've only installed it yesterday. There are a few programs I want to install.. both of which are a .tar.gz and a .tar.bz2 file. When I double click on them, they just ...
3
votes
1answer
256 views

Saw an interesting command but can't alias it

Saw an command from this post http://askubuntu.com/a/266839/75967 that I would like to alias find {,/usr}/{,s}bin -printf '%f\0' | xargs -0 whatis | sort | less I assume the less or the | is ...
3
votes
2answers
3k views

What is the difference between “source x”, “. x” and “./x” in Bash?

I have one bash source run.sh as follows, #!/bin/bash if [ $# -ne 1 ]; then exit fi ... when I execute it in two ways, there are different behaviors. The first way is, source run.sh It will ...
3
votes
2answers
3k views

Differences between fish and bash to pass commandline arguments to alias functions?

From the answers to my other question here i learned about the possibility to pass commandline arguments to a alias function in Bash. In Fish i can edit an alias by editing the file config.fish in ...
13
votes
3answers
410 views

Deleting input back to the last forward slash

I will very often be flitting between several files on a server. I will run the following example commands in sequence: nano /web/site/path/to/file /web/site/script.py nano ...
12
votes
2answers
9k views

Shell does not show typed in commands, “reset” works, but what happened?

My problem is that the Bash shell stops showing the characters I type into it. It does read the commands though. I've come across this problem quite a few times and I don't understand what causes it. ...
11
votes
5answers
13k views

Commandline shortcut for current directory similar to ~ for home directory?

When i use the cp or move command in a terminal window, i'm currently with bash in a certain folder like this. NES@server:~/Desktop/dir1$ And now i wanna copy a file from here ~/anotherdir/dir2 ...
10
votes
2answers
2k views

Pressing enter produces ^M instead of a newline

For example, if I am tail -fing a file or reading user input, <Enter> will produce ^M in the terminal instead of ending the read or adding a newline to stdout. ^J works fine. I'm sshing into ...
9
votes
2answers
1k views

What does the first '.' mean in '. ~/.bashrc'? [duplicate]

I saw a post about fix your alias in .bashrc. And he says after you put your alias in .bashrc , you need to use: . ~/.bashrc I do not quite understand what the first dot(' . ') does here. What's ...
8
votes
2answers
5k views

xclip on headless server

I've been using xclip to copy the output of bash commands like so: pwd | tr -d "\n" | xclip -selection c So that I can then paste the output into another terminal session. I was trying to use it ...
7
votes
1answer
179 views

Bash history keyboard shortcut for !*

In Bash, there are some handy operators to repeat parts of the last command: !^ expands to the first argument of the previous command, e.g., $ echo one "two three" one two three $ echo !^ echo one ...
7
votes
2answers
566 views

Get bash history to remember only the commands run with space prefixed!

The commands executed in the terminal prefixed with blank space(s) are not recorded in the command history file. But is there a way to get the reverse i.e. the history should only record those which ...
6
votes
2answers
7k views

What is my crontab -e local file path? I want to set it via BASH script

In my Ubuntu, my username is "meuser". When i do crontab -e, i can setup my rules. But instead of doing it with crontab -e, how can i do it directly to a file? Which file i cant modify?
6
votes
2answers
1k views

How do I use bash's “<<” operator?

I know bash has a >> operator, to append output to files, but what is the use of the << operator?
5
votes
2answers
803 views

How can I return to an application in the background?

I know that I can run an application in the background by putting an ampersand ('&') behind the command. For instance: user@ubuntu:~$ rtorrent & [1] 4618 starts rtorrent in the background. ...
5
votes
3answers
14k views

How to change directory using script

I have this script #!/bin/bash cd /home/user/somedir pwd it works as expected, but I would like this script to transport me to /home/user/somedir, but I stay in the same dir. How to write script ...