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

learn more… | top users | synonyms (1)

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
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?
19
votes
1answer
15k 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 ...
11
votes
5answers
32k views

How to pass the output of one command as the command-line argument to another?

So I have a script that, when I give it two addresses, will search two HTML links: echo http://maps.google.be/maps?saddr\=$1\&daddr\=$2 | sed 's/ /%/g' I want to send this to wget and then save ...
10
votes
1answer
657 views

How do I 'unbook' a pdf

I have a pdf file that was made into a booklet format. It is meant to print on A4 paper in landscape orientation; here are two pages in the pdf, which should correspond to four pages in the actual ...
5
votes
4answers
2k views

Copy text from one terminal into another

I am logged into ssh to a university account from my home computer. Then I find a file that I want to copy onto my local system. So I open a new shell terminal and am about to use scp to copy that ...
3
votes
4answers
1k views

What command do I use to see the start and end block of a file in the file system?

Is there any command that will output the beginning and ending blocks of any file?
16
votes
3answers
9k views

If you ^Z from a process, it gets “stopped”. How do you switch back in?

I accidentally "stopped" my telnet process. Now I can neither "switch back" into it, nor can I kill it (it won't respond to kill 92929, where 92929 is the processid.) So, my question is, if you have ...
9
votes
7answers
6k views

How do you bulk move files up one directory safely?

How can I move files up a directory where there might be hundreds or thousands of files in the directory, and you might not be sure about whether there are dupes in ... What method would you use? How ...
8
votes
6answers
280 views

Is there any program to provide a consistent interface across multiple archive types?

At the moment, if I download a compressed file, it could be any of a .tar.gz archive, a tar.bz2 arhive, a .zip archive or a .gz archive. And each time I do so, I have to remember what the command line ...
16
votes
3answers
26k views

Sort and count number of occurrence of lines

I have Apache logfile, access.log, how to count number of line occurrence in that file? for example the result of cut -f 7 -d ' ' | cut -d '?' -f 1 | tr '[:upper:]' '[:lower:]' is a.php b.php a.php ...
16
votes
4answers
9k views

Why do some commands 'hang' the terminal until they've finished?

Sometimes you run a program from the terminal, say, lxpanel†. The terminal won't drop you back to the prompt, it'll hang. You can press Ctrl+C to get back to the prompt, but that will kill ...
12
votes
5answers
669 views

Is there a more succinct alternative to piping to wc for counting files in a directory

If I do ls -1 target_dir | wc -l, I get a count of files in a directory. I find this a bit cumbersome. Is there a more elegant or succinct way?
11
votes
2answers
2k views

Where has the trailing newline char gone from my command substitution?

The following code best describes the situation.  Why is the last line not outputting the trailing newline char?  Each line's output is shown in the comment.  I'm using GNU bash, version 4.1.5 ...
10
votes
5answers
2k views

Combining large amount of files

I have ±10,000 files (res.1 - res.10000) all consisting of one column, and an equal number of rows. What I want is, in essence, simple; merge all files column-wise in a new file final.res. I have ...
10
votes
1answer
30k views

Always redirect error to /dev/null

I know I can redirect the error messages from a command to /dev/null using the following syntax: command arg1 arg2 2>/dev/null But is there a way to do this by default so that the error messages ...
10
votes
4answers
887 views

What is the easiest way to execute text from tail at the command line?

Sometimes I'm working on a new (ubuntu) box and I type git and am alerted: The program 'git' is currently not installed. You can install it by typing: apt-get install git-core If that happens I ...
9
votes
1answer
11k views

How to hide commands typed in a Linux shell?

Is there a way to hide what I'm typing in a shell, so the terminal doesn't echo my keystrokes, while still keeping the output of the command? For example, if I run ip addr show, the only thing on the ...
9
votes
2answers
8k views

How can I install ncdu on Red Hat?

The answers provided to this question doesn't help. I'ved tried yum install ncdu But I'm getting No package ncdu available
6
votes
4answers
735 views

How to print the name of missing files in a folder?

I have 2000+ files in a folder, but there are few files missing from the folder. Name of the files are like GLDAS_NOAH025SUBP_3H.A2003001.0000.001.2015210044609.pss.grb ...
6
votes
1answer
1k views

How to get bash to suggest a missing package?

While running Ubuntu, while trying to execute a commmand in bash, it used to suggest that the said program was missing but found in another package Y, and that I could try installing it. Now on a ...
5
votes
8answers
5k views

Run a command on all subfolders

If you have a series of subfolders (like from a to z) and want to run a command on each one of them (like rm *.pdf or ls *.pdf), how do you do that? The "manual" approach would be cd a, rm *.pdf, or ...
4
votes
7answers
1k views

Batch renaming of files [duplicate]

I have a directory full of images: DSCN4749.JPG DSCN4750.JPG DSCN4892.JPG ... And I would like a one-liner to rename them to (say). dscn4749.jpg dscn4750.jpg dscn4892.jpg ... How do I do this? ...
4
votes
3answers
858 views

Screenshot of non active window

How to take a screen shot of non active window? If I have 2 windows, I want to capture the screenshot of the one which is running in the background.
2
votes
1answer
339 views

Simpler processing of shell script options

I'm looking for way to process shell script arguments that is cleaner and more "self documenting" than getopt/getopts. It would need to provide... Full support of long options with or without a ...
19
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: > ...
16
votes
4answers
2k views

tar and its key letters: is it a bug or feature?

I am wondering to ask the difference of these two commands (i.e. only the order of their options are different): tar -zxvf foo.tar.gz tar -zfxv foo.tar.gz The first one ran perfectly but the ...
9
votes
2answers
2k views

Output ls -l size field with digits grouped by thousands?

It is possible to make ls -l output the size field with digits grouped by thousands? If so, how? For instance: $ ls -l -rw-rw---- 1 dahl dahl 43,210,052 2012-01-01 21:52 test.py (Note the commas ...
9
votes
2answers
5k views

How can I use ms-dos style wildcards with ls and mv?

I have the misfortune of coming from a MS-DOS background - but at least it makes me appreciate how much more powerful Linux is. I've been working on getting my Linux-Fu up to par, but there are a ...
8
votes
2answers
2k views

Directory “diff”?

I have two directories which are different versions of the same software package. I'd like to list all the files/directories that have changed between the two then copy those differences to a new ...
7
votes
0answers
123 views

How to filter any part of description or option from manpage [closed]

I want to get output of any desired description or option from a man page. Example: I want to get the description for the autoclean option from the apt-get man page: Please suggest a command, ...
7
votes
1answer
803 views

shebang line not working with cr-lf

Why are the shebang parts of the following elementary scripts not working: $ cat hello.sh #! /bin/sh echo Hello $ ./hello.sh bash: ./hello.sh: /bin/sh^M: bad interpreter: No such file or directory $ ...
6
votes
3answers
2k views

How to tweet using terminal?

I would like to tweet a message using terminal. I tried something like: curl -u 'TwitterUsername':'TwitterPassword' -d status=”Your Message Here” https://twitter.com/statuses/update.xml but seems ...
6
votes
2answers
8k views

How to execute one command on all files within a folder

Saying, I have this tree and I want to execute ruby on all scripts within the folder. How could I archive through one line of command. ./ ../ rb-script/ sample1.rb sample2.rb
6
votes
2answers
3k views

Problem in secure copying (scp) filenames with spaces

I am trying to copy files using secure copy(scp). I am trying to execute the following command but I get error due to the space in the absolute path of the location of the directory. scp -r -P 8484 ...
5
votes
3answers
4k views

Remove all lines in file A which contain the strings in file B

I have a CSV file users.csv with a list of userNames, userIDs, and other data: username, userid, sidebar_side, sidebar_colour "John Lennon", 90123412, "left", "blue" "Paul McCartny", 30923833, ...
5
votes
5answers
1k views

Is it possible to reference the most recently modified file in a command line argument?

I frequently download PDF files with heinous numeric file names from my browser. These automatically go into ~/Downloads. Ideally I would like to just be able to open these files with: evince "the ...
4
votes
2answers
7k views

Mounting Disk Image in Raw format [duplicate]

While Trying to mount a disk image in Raw(dd) format using the following command mount nps-2010-emails.dd /media/manu/ I get the following error message mount: you must specify the filesystem ...
3
votes
2answers
275 views

Assign specific line from a variable to another variable

I would like to take a specific line from a variable to another variable. I tried this but it doesn't work: c="1.apple 2.banna 3.peach" read "Please choose fruit [1-3]:" t a=$c | awk "NR==$t" echo ...
3
votes
2answers
218 views

What can I do if bash stops echoing?

One of the applications I use at work sometimes screws with my bash and so I don't see my own input anymore. I.e. $ echo foo foo $ becomes $ foo $ I incorrectly tried to run stty -echo which ...
2
votes
3answers
12k views

UNIX commands help - find

I'm trying to learn UNIX commands and I'm playing this game to learn and I'm really stuck at the moment. I'm in a server through ssh and the directory is full of random files and folders and the ...
0
votes
2answers
3k views

grep: input file 'X' is also the output

I use ubuntu 14.4, and attempt to redirect the output of grep command to a file, but I keep getting this error: grep: input file 'X' is also the output I've searched for this issue and just found ...
-1
votes
5answers
707 views

Why, still in modern GUI-based Linux distros, is it common to use the command line? [closed]

Is the command line a popular choice thing, or do I have something wrong here? In modern Linux there's dozens of fresh, robust, 3-D rendered GUIs, graphical-based APIs, and desktop interfaces that ...
19
votes
6answers
1k 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 ...
10
votes
2answers
3k views

Check ping statistics without stopping

Is there a way to tell ping to show its usual termination statistics without stopping the execution? For instance, I'd like to quickly view: --- 8.8.8.8 ping statistics --- 2410 packets transmitted, ...
10
votes
3answers
16k views

Characters encodings supported by more, cat and less

I have a text file encoded as following according to file: ISO-8859 text, with CRLF line terminators This file contains French's text with accents. My shell is able to display accent and emacs ...
9
votes
2answers
2k views

What does “-” mean as an argument to a command?

I found this link on how to open tgz in one step. gzip -dc target.tar.gz | tar xf - What does the '-' mean?
8
votes
5answers
18k views

How to display line number while doing grep on a file

How to display line number while doing grep on a file. For example: grep CONFIG_PM_ADVANCED_DEBUG /boot/config-`uname -r
8
votes
4answers
16k views

How to install software on Red Hat?

What's the simplest way to download/install software on Red Hat Linux (from bash command line)?
7
votes
4answers
3k views

How can I check if a gzipped file is empty?

Is there a quick way to check if a gzipped file is empty, or do I have to unzip it first? example: $ touch foo $ if [ -s foo ]; then echo not empty; fi $ gzip foo $ if [ -s foo.gz ]; then echo not ...