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

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26
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5answers
13k views

What is the difference between ls and l? [duplicate]

I accidentally typed l instead of ls today and found that the command still printed a list of the files in my current directory. Trying l --help brings up the help file for ls suggesting that l is ...
26
votes
8answers
2k views

Dealing with file names with special first characters (ex. ♫)

I have recently come across a file whose name begins with the character '♫'. I wanted to copy this file, feed it into ffmpeg, and reference it in various other ways in the terminal. I usually ...
26
votes
2answers
47k views

How to use command line to change volume?

I am trying to control the volume using my programming script. How can I do the following in Fedora 15, Ubuntu linux? Mute/ Unmute Volume up and volume down Note: Please note that I use a web USB ...
26
votes
2answers
101k views

Sending messages to another user

Is there any command to send messages through the Linux shell to other people on the same network? I'm using write user and then write the message itself. But there's any command that doesn't show my ...
26
votes
4answers
134k 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 ...
26
votes
5answers
49k views

How can I make a program executable from everywhere

What should I do if I want to be able to run a given program regardless of my current directory? Should I create a symbolic link to the program in the /bin folder?
25
votes
4answers
3k views

Is it possible to define a command in bash?

For example, can I set gb = cd /media/Dan/evolution So that everytime I execute gb in bash, I can cd to that particular directory? I find something online, alias command. But It seems can't do the ...
25
votes
5answers
27k views

How can I get a formatted date for a UNIX timestamp from the command line

I have a UNIX timestamp and I'd like to get a formatted date (like the output of date) corresponding to that timestamp. My attempts so far: $ date +%s 1282367908 $ date -d 1282367908 date: invalid ...
25
votes
2answers
87k views

How to display open file descriptors but not using lsof command

Hi I have read Here that lsof is not an accurate way of getting the number of File Descriptors that are currently open. He recommended to use this command instead cat /proc/sys/fs/file-nr While ...
25
votes
9answers
2k views

How to tell what type of filesystem you're on?

Is there a command to tell what type of filesystem you're using?
25
votes
2answers
5k views

disable CTRL-D window close in terminator (terminal emulator)

I am often logged in through multiple SSH sessions. To logout from my sessions, I press CTRL+d, until I am back on my local machine. However, sometimes I press once too many, and my terminal exits. ...
25
votes
2answers
12k views

Is it possible to save as sudo from nano after you've forgotten to run as sudo?

A lot of the time I edit a file with nano, try to save and get a permission error because I forgot to run it as sudo. Is there some quick way I can become sudo without having to re-open and re-edit ...
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 ...
24
votes
14answers
31k views

What's a good example of piping commands together?

If you were helping someone to learn the concept of pipes on the command line what example would you use? The example that actually came up was as follows: cat whatever.txt | less I feel like ...
24
votes
4answers
4k views

Is it possible to configure ctrl-w (delete word)?

Normally, Ctrl+W deletes back to the last whitespace. Is it possible to configure it to use additional characters, such as /? Edit: To be more clear: I don't want to configure the key for it, I want ...
24
votes
4answers
21k views

How to Execute multiple command using nohup

I need to execute multiple commands using nohup. Each command should be executed after the previous command. I used this command as an example: nohup wget $url && wget $url2 > /dev/null ...
24
votes
1answer
8k views

How do we specify multiple ignore patterns for `tree` command?

I need to print the directory structure of our production system and I would like to remove some specific directories from the tree? How do we specify multiple ignore patterns for tree command?
24
votes
1answer
67k views

How do I get sar to show for the previous day?

on our servers, typing sar show's the system load statistics for today starting at midnight, is it possible to show yesterdays statistics?
23
votes
2answers
3k views

Create a test file with lots of zero bytes

I know how to create an empty file: touch /var/tmp/nullbytes but how can I create a 1MB file that only contains nullbytes on the commandline with bash?
23
votes
6answers
46k views

Linux ls to show only filename date and size

How can I use ls in linux to get a listing of filenames date and size only. I don't need to see the other info such as owner or permission. Is this possible?
23
votes
3answers
16k views

Why isn't there any shell command to create files?

Attention please: I am not asking how to make a file from the command line! I have been using touch for making files for years without paying attention that its main purpose is something else. If ...
23
votes
3answers
2k views

How can I shutdown a RHEL server at 06:45 tomorrow morning?

I just received notification that our site has a power outage tomorrow morning. I am a Windows admin but I have to cover for our Linux admin who's not around until tomorrow evening. I need to ...
23
votes
4answers
21k views

What is the meaning of IFS=$'\n' in bash scripting ?

at the beginning of a shell script program in the bash is the following line: IFS=$'\n' What is the meaning behind this collection of symbols ?
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 ...
23
votes
6answers
27k views

How do I limit the number of files printed by ls?

Is there a way to limit the quantity of listed files on a ls command? I've seen: ls | head -4 but to get head or tail to be executed I need to wait for ls to finish execution, and with directories ...
23
votes
1answer
44k views

Using --exclude with the du command

This is probably something basic but I'm not able to make it work. I'm trying to use DU to get a total size of files minus certain directories. I need to exclude one specific directory called uploads ...
22
votes
4answers
34k views

How do I make multiple directories at once in a directory?

I know with mkdir I can do mkdir A B C D E F to create each directory. How do I create directories A-Z or 1-100 with out typing in each letter or number?
22
votes
8answers
1k views

Clipboard for copying and pasting files in command line?

In Bash, suppose I visit a directory, and then another directory. I would like to copy a file from the first directory to the second directory, but without specifying the long pathnames of them. Is it ...
22
votes
4answers
47k views

Grabbing the first [x] characters for a string from a pipe

If I have really long output from a command (single line) but I know I only want the first [x] (let's say 8) characters of the output, what's the easiest way to get that? There aren't any delimiters.
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 ...
22
votes
3answers
14k views

how to download a file using just bash and nothing else (no curl, wget, perl, etc.)

I have a minimal headless *nix which does not have any command line utilities for downloading files (e.g. no curl, wget, etc). I only have bash. How can I download a file? Ideally, I would like a ...
22
votes
3answers
10k views

Use & (ampersand) in single line bash loop

I have been using this command successfully, which changes a variable in a config file then executes a Python script within a loop: for((i=114;i<=255;i+=1)); do echo $i > numbers.txt;python ...
22
votes
8answers
9k views

How to efficiently generate large, uniformly distributed, random integers in bash?

I have been wondering what would be the best way to get good randomness in bash, i.e., what would be a procedure to get a random positive integer between MIN and MAX such that The range can be ...
22
votes
4answers
20k views

What is the purpose of the 'install' command?

I've seen the install command used in a lot of Makefiles, and its existence and usage are kind of confusing. From the manpages, it seems like a knockoff of cp with less features, but I assume it ...
22
votes
4answers
16k views

Count number of lines of output from previous program

I'm trying to count the number of lines of output a certain program produces. The problem is, the program takes a long time to run, and I want to display the output to the user. Is there a way to ...
22
votes
1answer
2k views

Is there a standard command that always exits with a failure?

I want to test my script with a command that fails. I could use an existing command with bad arguments. I could also write a simple script that immediately exits with a failure. Both of these are easy ...
21
votes
5answers
7k views

Why is echo a shell built in command?

$ which echo echo: shell built-in command. $ which ls /bin/ls $ which cat /bin/cat Why is echo not an independent utility like ls, ps, cat etc? Why is it shell specific? Any good reasons?
21
votes
9answers
39k views

Generate random numbers in specific range

After googling a bit I couldn't find a simple way to use a shell command to generate a random decimal integer number included in a specific range, that is between a minimum and a maximum. I read ...
21
votes
2answers
1k views

How do I move all files output from a command?

I have this grep command to find files without the word Attachments in them. grep -L -- Attachments * I want to move all the files that are output from that command. How do I do that in bash? Do I ...
21
votes
4answers
1k views

Is it possible to redirect the output of a command into more than one command?

As far as I know, I can use the tee command to split the standard output onto the screen and further files: command -option1 -option2 argument | tee file1 file2 file3 Is it possible to redirect ...
21
votes
5answers
219k views

How to create a simple .txt (text) file using terminal? [closed]

I'm just trying to review basic terminal commands. Having said that, how do I create a text file using the terminal only?
21
votes
5answers
7k views

How can I remove duplicates in my .bash_history, preserving order?

I really enjoying using control+r to recursively search my command history. I've found a few good options I like to use with it: # ignore duplicate commands, ignore commands starting with a space ...
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" ...
21
votes
1answer
2k views

Should the usage message go to stderr or stdout?

Should the usage message which is printed with e.g. command -? of a Unix command go to stderr or stdout, and why? Should it go to the same place if the user makes a mistake with an option?
21
votes
3answers
665 views

The precedence of command options?

I know that rm -f file1 will forcefully remove file1 without prompting me. I also know that rm -i file1 will first prompt me before removing file1 Now if you execute rm -if file1, this will also ...
21
votes
3answers
1k views

Can other users view the arguments passed to a command?

If I invoke a command with arguments like so: bob@bob-pc:~$ command -arg1 -arg2 ...can other users view the arguments passed to the command?
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 ...
21
votes
5answers
2k views

How to run a command at an average of 5 times per second?

I have a command-line script that performs an API call and updates a database with the results. I have a limit of 5 API calls per second with the API provider. The script takes more than 0.2 seconds ...
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 ...
21
votes
5answers
6k views

Command line friendly spreadsheets

Does such a thing exist? Text-based spreadsheets that display well in a CLI environment. I'm aware that I could cat foobar.csvand do as I please, but it isn't particularly practical or attractive. I ...