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

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22
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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
304 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
2answers
1k 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
5
votes
1answer
3k 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 ...
3
votes
2answers
796 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 ...
9
votes
2answers
9k 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 ...
53
votes
12answers
70k views

Efficiently delete large directory containing thousands of files

We have an issue with a folder becoming unwieldy with hundreds of thousands of tiny files. There are so many files that performing rm -rf returns an error and instead what we need to do is something ...
36
votes
3answers
16k 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 ...
14
votes
1answer
2k 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 ...
16
votes
4answers
18k 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 ...
23
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 ...
24
votes
3answers
14k 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
2answers
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
625 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
26k 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
928 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 ...
9
votes
4answers
21k 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
3k 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 ...
9
votes
3answers
9k 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
648 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"?
123
votes
8answers
53k 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. ...
90
votes
4answers
84k views

How to tell gzip to keep original file?

I would like to compress a text file using gzip command line tool while keeping the original file. By default running the following command gzip file.txt results in modifying this file and renaming ...
22
votes
4answers
108k 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 ...
60
votes
8answers
121k 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.
30
votes
3answers
39k 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 ...
35
votes
4answers
50k views

Usage of dash (-) in place of a filename

For a command, if using - as an argument in place of a file name will mean STDIN or STDOUT. But in this example, it creates a file with the name -: echo hello > - How can I make - in this ...
17
votes
1answer
20k views

command to zip multiple directories into individual zip files

I have a single directory that contains dozens of directories inside of it. I'm new to command line and I'm struggling to come up with a command that will zip each sub-directory into a unique ...
15
votes
2answers
7k views

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

This question follows directly from the answer to one of my previous questions here. I am newbie to unix world and this site has helped a lot to understand some core concepts. In this case I am ...
20
votes
6answers
4k 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
17k 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 ...
13
votes
3answers
14k 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
6k 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 ...
32
votes
5answers
10k 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: ...
20
votes
7answers
4k 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 ...
19
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" ...
27
votes
6answers
34k 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 ...
25
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 ...
24
votes
7answers
10k 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 ...
19
votes
6answers
11k 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 ...
14
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?
25
votes
1answer
25k 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 ...
19
votes
3answers
6k views

Command for forcing a pointer ungrab (captured mouse release)

Sometimes Firefox doesn't release the mouse after dragging, so I need to kill the application to force it to release its pointer grab. Is there any command to force an application to ungrab the ...
10
votes
3answers
1k views

Lowercasing all directories under a directory

I want to lowercase every directories' name under a directory. With which commands can I do that?
9
votes
1answer
2k views

Searching for a command line tagging tool for mp3 and ogg that supports pictures

I am searching a command-line tagging tool that supports ogg- and mp3-tagging and allows to add a picture to the tags. Currently I use lltag but that does not support pictures. dagger is the tool I ...
8
votes
4answers
1k views

Bash: Capture / Use last (or Nth) line in stdout

Query I use Bash. When I'm looking for files, often I'll do the following: find -name stackexchange.hs And often the results will look like: /youre/the/man/now/dog/stackexchange.hs ...
5
votes
4answers
2k views

How to remove URI encoding from file names?

I realise this might be quite a simple question, but I'm still quite new to the command line and only have a grasp of basic commands. I've downloaded some lecture presentations (~25 or so) from my ...
5
votes
3answers
3k views

How can I expand a relative path at the command line, with tab completion?

In bash is there any way to expand a relative path into an absolute path, perhaps with tab completion? I ask because sometimes I will search for a file, find it, then vim it: cd /etc cd apache2 cd ...
5
votes
4answers
2k views

Delete everything except a few extensions

Can I modify the rm command with regular expression or something to delete. every file in current directory except files with extensions *.bmp, *.wav and *.png? It should be case insensitive because ...
6
votes
3answers
5k views

What's wrong with these two cron job's?

I have the following cron jobs defined. 55 8 * * 3 /usr/bin/php /home/mark/dev/processes/customClient/events.php > /home/mark/dev/processes/customClient/events-`date +%Y-%m-%d ...