The command-line is the interactive interface to your shell.

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45
votes
11answers
38k views

Which mp3 tagging tool for Linux?

Which app would you recommend for Linux to tag MP3s? Under Windows I used to use tag&rename and liked it a lot; it works well under Wine, but I want something that runs natively
38
votes
5answers
11k views

How to echo a bang!

I tried to create a script by echo'ing the contents into a file, instead of opening it with a editor echo -e "#!/bin/bash \n /usr/bin/command args" > .scripts/command The output: bash: ...
32
votes
8answers
75k views

Do we have an undo in Linux?

I renamed a few files in one batch script. Is there a way to undo the changes without having to rename them back? Does Linux provide some native way of undoing?
19
votes
5answers
63k views

Pass the output of previous command to next as an argument

I've a command that outputs data to stdout (command1 -p=aaa -v=bbb -i=4). The output line can have the following value: rate (10%) - name: value - 10Kbps I want to grep that output in order to ...
11
votes
2answers
3k views

When do su and sudo use different passwords?

I am able to run anything using sudo; my password is accepted. But whenever I try to do su from a shell, it fails with: su: incorrect password What can the problem be?
23
votes
2answers
2k views

Is there a reason why ls does not have a --zero or -0 option

This question was prompted by questions about ls' -1 option and the recurring tendency of people to ask question and answers that includes processing the output of ls. This reuse of the output ls ...
22
votes
4answers
1k views

Are Linux utilities smart when running piped commands?

I was just running a few commands in a terminal and I started wondering, does Unix/Linux take shortcuts when running piped commands? For example, let's say I have a file with one million lines, the ...
12
votes
2answers
330 views

`test` and `[` - different binaries, any difference?

I noticed while answering another question that test and [ are different binaries, but the [ manpage pulls up test's. Besides the requirement for an ending ], is there any difference? If not, why are ...
7
votes
1answer
5k views

Zip the contents of a folder without including the folder itself

I have a directory called folder that looks like this: folder -> root_folder -> some files I want to zip this directory into zipped_dir, I tried: zip -r ...
7
votes
2answers
2k views

grep - why do brackets in grep pattern remove the grep process from ps results?

Why do brackets in a grep pattern remove the grep process from ps results? $ ps -ef | grep XXXX [...] XXXX [...] grep XXXX $ ps -ef | grep [X]XXX [...] XXXX
3
votes
2answers
897 views

`free`: output format

I use free to get the amount of free space on some of my servers. Its output is something like: $ free -m total used free shared buffers cached Mem: 374 ...
11
votes
2answers
11k views

What does the tilde (~) mean at the end of a filename? [duplicate]

What is the file with the ~ at the end of the filename for? $ ls # aliased to add flags -rwxrwxr-x 1 durrantm 2741 May 16 09:28 strip_out_rspec_prep_cmds.sh~* drwxrwxr-x 13 durrantm 4096 May 16 ...
26
votes
4answers
135k views

Connecting to wifi network through command line

I am trying to connect to my WEP network just using the command-line (Linux). I run: sudo iwconfig wlan0 mode Managed essid 'my_network' key 'xx:xx:... hex key, 26 digits' Then I try to obtain an ...
66
votes
11answers
80k views

How do I convert an epoch timestamp to a human readable format on the cli?

How do I convert an epoch timestamp to a human readable format on the cli? I think there's a way to do it with date but the syntax eludes me (other ways welcome).
38
votes
3answers
19k views

How can I “relink” a lot of broken symlinks?

I have a directory tree which has a bunch of symbolic links to files under /home... however, I have moved /home to /mnt/home and need a way to "relink" all of the symlinks. Does such functionality ...
48
votes
2answers
40k views

How to suspend and resume processes

In the bash terminal I can hit Control+Z to suspend any running process... then I can type fg to resume the process. Is it possible to suspend a process if I only have it's PID? And if so, what ...
14
votes
1answer
3k 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 ...
24
votes
10answers
4k views

Run two commands on one argument (without scripting)

How can I perform two commands on one input, without typing that input twice? For example, the stat command tells a lot about a file, but doesn't indicate its file type: stat fileName The file ...
19
votes
5answers
21k views

find n most frequent words in a file

I want to find, say, 10 most common word in a text file. Firstly, solution should be optimized for keystrokes (in other words - my time). Secondly, for the performance. Here is what I have so far to ...
27
votes
3answers
19k views

How to execute consecutive commands from history?

Suppose I want to execute a sequence of four commands that I have executed before. If the first one is 432 in the command-history, then I could do: $ !432; !433; !434; !435 I'm curious, is there a ...
8
votes
3answers
5k views

Show a notification across all running X displays

Using the command line, I'd like show a notification on every running X display. ( and running console ) Something like: notify-send-all 'Warning' 'Nuclear launch in 5 minutes, please evacuate' Is ...
10
votes
3answers
663 views

syntax_highlight <source_file> | lpr

Does anyone know of a simple way to produce the PostScript corresponding to a syntax-highlighted version of a source file that can be piped directly to a PostScript printer? As the wording of the ...
10
votes
4answers
28k views

Getting all files that have been modified on a specific date

Is it possible to find all php files within a certain directory that have been modified on a certain date I'm using find /var/www/html/dir/ -mtime -28 | grep '\.php' to get files modified within ...
9
votes
3answers
964 views

How to pipe the list of commands displayed by of “tab complete”?

When using commands in bash I like the double tab option to display the available commands. Some commands have more possible matches than others: Is there a way I can pipe the output of the double ...
10
votes
4answers
23k views

How to use /dev/fb0 as a console from userspace, or output text to it

So I have a Palm Pre (original P100EWW) model that I enabled developer mode on, and installed a Debian Squeeze chroot. Works great. I have plans to use this for ANYTHING (bittorrent peer, web ...
8
votes
3answers
4k views

How do you send command line apps directly to the background? [duplicate]

I already know that pressing ctrl+z stops the app, then I can send the app to background with the bg command, but that means there is a brief preiod of time that the app is stopped. How do I send the ...
2
votes
1answer
11k views

How to round floating point numbers in shell?

How do I correctly round IEEE 754 floating point numbers on the command line? I want to specify the precision of the output number - the count of fractional digits. Rounding 6.66 to precision 1 ...
10
votes
4answers
11k views

How to revert chown command?

If I run: sudo chown -R user:user / Can I revert it to what it was before I ran it?
8
votes
5answers
2k views

xargs and vi - “Input is not from a terminal”

I have about 10 php.ini files on my system, located all over the place, and I wanted to quickly browse through them. I tried this command: locate php.ini | xargs vi But vi warns me Input is not ...
7
votes
4answers
662 views

How can I find a file whose name includes a given string, such as “abcde”?

Within a set of directories, how do I find a file whose name includes a given string, such as "abcde"?
134
votes
8answers
61k views

How can I find broken symlinks

Is there a way to find all symbolic links that don't point anywere? find ./ -type l will give me all symbolic links, but makes no distinction between links that go somewhere and links that don't. ...
64
votes
6answers
58k views

Is there a tool to get the lines in one file that are not in another?

Is there any tool that can get lines which file A contains, but file B doesn't? I could make a little simple script with, e.g, perl, but if something like that already exists, I'll save my time from ...
32
votes
9answers
138k 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 ...
63
votes
8answers
136k views

How do I make my pc speaker beep

Using bash, how can I make the pc speaker beep? Something like echo 'beepsound' > /dev/pcspkr would be nice.
32
votes
4answers
44k 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 ...
20
votes
2answers
8k views

What is meant by a shell is in “vi” mode or “emacs” mode?

This question follows directly from the answer. In this case I am specifically unable to understand the part which says: In that regard, its behaviour is closer to emacs' than with ...
21
votes
6answers
5k views

put history command onto command line without executing it

I use !n where (n) is the line number for executing a line in the history file I want executed at the command prompt which I find via history|less. But there is a command line history event I wish ...
14
votes
6answers
18k views

Deleting all files in a folder except files X, Y, and Z

I have a lot of files and folders in a specific folder and I want to delete all of them; however, I wanted to keep files X, Y, and Z. Is there a way I can do something like: rm * | but NOT grep | X ...
21
votes
7answers
5k views

Command-line-friendly full-text indexing?

Is there such a thing as a full-text indexing engine, that can be queried from the command line and ideally wouldn't require using a gui at all ? I'm especially interested in indexing my ebooks and ...
16
votes
3answers
15k views

How can I move files by type recursively from a directory and its sub-directories to another directory?

What would be a good way to move a file type from a directory and all of its sub-directories? Like "move all *.ogg in /thisdir recursively to /somedir". I tried a couple of things; my best effort was ...
6
votes
4answers
7k views

All commands that should be used to connect to wifi in command line

I would like to switch from gnome to awesome and I would like to connect my wifi network in command line (instead of using gnome tools). So, I searched on the internet and found approximatively the ...
21
votes
2answers
2k views

^x^y unix trick for all instances in last command?

One of my favorite Unix tricks is ^x^y, which will take the last command and replace the first instance of "x" with "y". However, I'm wondering if a similar trick works to replace all instances of "x" ...
11
votes
3answers
3k views

Is there a way to simulate a “Close” event on various windows using the terminal?

I answered on Ask Ubuntu Quit all instances of gnome-terminal via a command but as you all can read gnome-terminal didn't seems to have a SIGcall I could use to simulate this "Close" event. So this ...
34
votes
2answers
40k 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 ...
28
votes
6answers
41k views

Sorting files according to size recursively

how to scan a folder recursively and find the largest files in the folder, and sort them by size. I have tried using ls -R -S but it tends to list the directories as well I need to scan the folders ...
28
votes
1answer
30k views

How to display kernel command line parameters?

In the grub.conf configuration file I can specify command line parameters that the kernel will use, i.e.: kernel /boot/kernel-3-2-1-gentoo root=/dev/sda1 vga=791 After booting a given kernel, is ...
28
votes
4answers
6k views

How can I display syntax highlighting on a file?

Is there a variant of cat that outputs syntax-highlighted lines of code when used on a source file? An idea: maybe vi[m] or another editor can be asked to dump the syntax-highlighted contents of said ...
28
votes
7answers
12k views

Isn't less just more?

When I do more filename and less filename, it would seem that the resulting terminals are quite similar. I can navigate and search through my files identically (j, Space, /pattern, etc.). I find it ...
20
votes
6answers
12k views

How to display numbers in reverse order using seq(1)?

I have iterate over numbers in various order. I am able to display them in increasing order, even with steps like: $ seq --separator="," 1 10 1,2,3,4,5,6,7,8,9,10 $ seq --separator="," 1 2 10 ...
15
votes
4answers
10k views

How do I merge two *.avi files into one

I have two *.avi files: sequence1.avi sequence2.avi How do I merge these two files using a command-line or GUI?