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

learn more… | top users | synonyms (1)

24
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 ...
24
votes
7answers
9k views

Converting colored output into html

There are tools providing coloured output: dwdiff -c File1 File2 # word level diff grep --color=always # we all know this guy ... The question is: How to convert their colored output of arbitrary ...
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 ...
23
votes
3answers
1k 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
11answers
27k 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 ...
23
votes
7answers
6k views

how to glob every hidden file except current and parent directory [duplicate]

I want to glob every hidden file and directory, but not the current (.) and parent directory (..). I am using bash. Observe current behaviour: $ ls -a . .. ...a ...aa ..a ..aa .a .aa .aaa ...
22
votes
4answers
31k 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
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 ...
22
votes
4answers
106k 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 ...
22
votes
1answer
7k 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?
22
votes
4answers
18k views

How to Execute multiple command using nohup

I want to execute multiple command using nohup, And each command should execute after previous command, I used this command for example: nohup wget $url && wget $url2 > /dev/null ...
21
votes
5answers
69k views

count lines in a file

I'm sure there are many ways to do this: how can I count the number of lines in a text file? $ <cmd> file.txt 1020 lines
21
votes
6answers
38k 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?
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
4answers
39k 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.
21
votes
3answers
12k 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 ...
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
5answers
39k 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?
21
votes
8answers
8k 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 ...
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 ...
20
votes
5answers
6k 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?
20
votes
2answers
2k 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?
20
votes
3answers
12k 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 ...
20
votes
4answers
11k 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 ?
20
votes
3answers
572 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 ...
20
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?
20
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 ...
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 ...
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
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 ...
19
votes
5answers
1k views

Commands to learn about an unfamiliar system [closed]

You log in to an unfamiliar UNIX or Linux system (as root). Which commands do you run to orient yourself and figure out what kind of system you are on? How do you figure out what type of hardware is ...
19
votes
5answers
23k 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 ...
19
votes
4answers
2k views

What should I use when cut doesn't cut it?

I have a file cities like this: [1598] San Diego, US (inactive) [4517] St Louis, US (inactive) [6346] Orlando, US (inactive) I want to cut out the city names, so that I have: San Diego St Louis ...
19
votes
2answers
4k 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. ...
19
votes
3answers
29k views

How do I remove all sub-directories from within a directory?

This question is kind of a phase II to the first question I posted at here I have a directory that contains a bunch of sub-directories, .zip files, and other random files not contained within a ...
19
votes
4answers
6k 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 ...
19
votes
3answers
5k views

IP to Country console command

Is there a console command that takes an IP address as an input and shows its geographical information like city, country, ISP, etc.?
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" ...
19
votes
2answers
40k 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 ...
19
votes
4answers
16k 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 ...
19
votes
1answer
2k views

zsh Interpret/ignore commands beginning with '#' as comments

In bash, if I type a command beginning with a '#', bash ignores it as a comment. Ie, the following is ignored at the bash prompt: > # Hi there! Whereas in zsh: > # Hi there ! zsh: bad ...
19
votes
1answer
38k 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 ...
19
votes
1answer
13k views

What do double slashes mean in UNIX path? Is `cd dir/subdir//` valid? [duplicate]

Possible Duplicate: How linux handles multiple path separators (/home////username///file) Do cd dir/subdir/ and cd dir/subdir// mean the same in UNIX? Will the later work out? Else does ...
19
votes
6answers
922 views

Why is aliasing over standard commands not recommended?

For example, a common alias I've seen in the ~/.bashrc file (or equivalents) is alias rm='rm -i' However, I've seen people recommend against this because the alias might not exist on another ...
19
votes
2answers
2k views

Coloring different sources for tail

I'm watching different logs by tail -q -f /var/log/syslog -f /var/log/fail2ban.log -f /var/log/nginx/error.log How can I have the output of each log colored differently?
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 ...
18
votes
5answers
2k views

Why do I sometimes get repeatedly prompted with “>” in the terminal?

Alright, when I run certain commands the wrong way, (misspelled, etc.) The terminal outputs this: > instead of computername:workingfolder username$, and when I type enter it goes like this: > ...
18
votes
9answers
3k views

How to make sure that a command is not interrupted, even if terminal is closed? [duplicate]

In Linux. Say I want to run a command and it takes too long. I just want to ensure it's done. How?