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

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5
votes
8answers
4k 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
3answers
731 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.
3
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? ...
2
votes
1answer
8k 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 ...
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: > ...
15
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
1answer
10k 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 ...
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
2answers
17k 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 ...
7
votes
0answers
122 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
701 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
1answer
909 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 ...
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 ...
5
votes
3answers
3k 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, ...
4
votes
5answers
933 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 ...
3
votes
2answers
238 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
170 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
959 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?
2
votes
3answers
9k 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
2k 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 ...
0
votes
5answers
664 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
925 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
3answers
14k 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
1k 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
4answers
14k 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
5answers
15k 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
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 ...
6
votes
7answers
4k views

What is the easiest way to add a string on the beginning of every line of the file from the command line?

I am looking for a way to add some string to the beginning of every line (same string for every line). Not something customizable but rather something that will be easy to remember and available on ...
6
votes
1answer
346 views

Output redirection and spaces

I'm paranoid about this, but hopefully it's a simple question: Is there any difference between cat file1 | egrep -oP "[Mm]y string" > /home/user/file.txt and cat file1|egrep -oP "[Mm]y ...
5
votes
4answers
986 views

How to move all files inside present subfolders up here

I have 50 folders with some subfolders too, with more than 1000 audio files total. I need to remove all subfolders and put all files in present level. Tried mv */* ./ but it complaints: argument list ...
5
votes
5answers
2k views

Multiple ssh sessions in single command

I'm trying to copy a database from one server to another. I tried using the following command and it's getting tied up on entering the ssh passwords. If I put in one server's password, it complains ...
4
votes
2answers
10k views

Sending a file as the body of an email

I want a utility that does something like this: email --subject="xxx" --body=body.txt --to=to_address@hostname.com (using pre-configured sender information for e.g. gmail). Note that body.txt is ...
4
votes
2answers
4k views

Why doesn't tar ask before overwriting existing files?

I lost a couple hundred lines of a Vim plugin I wrote and continue back up every so often because I extracted a tar file containing an older version. I decided not to use source control management ...
3
votes
1answer
214 views

What is 'ls quote'?

Today I happened to press ' after ls So the command is ls' After I issued this command: [edit]Seems the image can't display properly > ls' quote> ls' zsh: command not found: ls\nls > ...
3
votes
2answers
6k views

How do I run a command on multiple files

This is pretty basic, I have a folder with several subfolders of JS files and i want to run Google's Clojure compiler on all of the files in those folders. The command to process a single file is as ...
3
votes
2answers
871 views

View all user's printing jobs from the command line

I'm running Fedora 17, Gnome (3?), and using bash from terminal. Whenever I run lpstat I only get a list of my jobs, but every time I go to retrieve my jobs from the printer, somebody else is ...
3
votes
1answer
319 views

How to use SCSUDO to run scripts with positional parameters?

I am trying to use scsudo to run a number of defined commands to stop and start processes on a UNIX host. The issue I am experiencing is that scsudo does not seem to like the use of positional ...
2
votes
2answers
1k views

“cat” command: how to automatically escape everything that might be a violation?

If you copy the contents of httpd.conf and then paste it into a cat command.. such as this one.. #!/bin/bash cat > /test << EOF pasted here.. EOF you run into this error: -bash: ...
2
votes
3answers
412 views

How to get a list of applications associated with a file using command line

File associations usually are made in the desktop environment, but how to get a list of applications associated with a file using command line? Something like: $ getassoc foo.pdf <CR> $ ...
2
votes
3answers
2k views

ssh: execute a command before login

I am looking for a way to execute a local command when logging into a remote machine via SSH. (I want to stay logged in after the command has finished.) In other words, I want to specify the command ...
2
votes
1answer
187 views

cp : short way of copying [closed]

I don't remember exactly but there was either cp or mv command which I was able to do something like this with: cp file{.cpp, .cpp.org} Which would copy file.cpp and make a copy named file.cpp.org. ...
2
votes
3answers
3k views

Why does Firefox refuse to die despite killing it with pkill -9?

I am issuing the following command to kill Firefox on my Red Hat Linux box: [subhrcho@slc04lyo ~]$ pkill -9 -f firefox [subhrcho@slc04lyo ~]$ However, when I try to invoke Firefox through ...
2
votes
4answers
4k views

Renaming files works, but soft links point to the old names. How can I fix that?

For example, I'm renaming many files inside a tree like this: [bash]$ for file in `find . -name "*gsf*"`; do `mv $file ${file/gsf/msf}`; done That renames all the instances of "gsf" in file names ...
1
vote
1answer
236 views

Operate X clipboard from command line

I'd like to copy and paste to the clipboard from the command line. I've found two utilities that works with "mouse" selection: xclip and xsel. But they both ignore the clipboard that is filled with ...
1
vote
2answers
461 views

Why does “grep '.*[s]' file” work and “grep .*[s] file” doesn't?

Comparing grep '.*[s]' file with grep .*[s] file Why do you need quotation marks to let this work properly? In the second case, grep seems trying to inspect every file with a period.
1
vote
1answer
202 views

Using cURL command-line tool on Mac, how does one fetch stock data which comes back *without* commas? [duplicate]

The below script is not working. cd desktop/quoteUpdate while true do curl-o quotes.txt -s "http://download.finance.yahoo.com/d/quotes.csv?s=goog,aapl&f=sl1" sed -i '.bak' 's/,/ /g' quotes.txt ...
1
vote
2answers
8k views

How to unpack a downloaded tar.bz2 archive?

I downloaded YOONO-Desktop from http://www.yoono.com/, and I try to install it with the following steps: [root@localhost mpatil]# tar xfv yoono-destop-1.8.43.tar tar: yoono-destop-1.8.43.tar: Cannot ...
1
vote
3answers
844 views

piping pwd to an executable as an argument

So I have an alias for "sublime text" http://www.sublimetext.com/docs/2/osx_command_line.html and very often I need to open a file or a folder right from the terminal, easy for a file: subl ...
0
votes
1answer
31 views

extract subfolders outside and rename if necessary

I have a directory looks like: dhcp-18-189-47-44:CE-06-new-stuctures_backup wenxuanhuang$ ls DFT-00001 DFT-00004 DFT-00007 DFT-00010 DFT-00013 DFT-00016 DFT-00019 DFT-00022 DFT-00025 DFT-00028 ...