The shell is unix's command-line interface. You can type commands in a shell interactively, or write scripts to automate tasks. Use this tag for questions applying to /bin/sh and most compatible shells (ash, bash, ksh, zsh, …).

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Can you specify a separate trap in a subshell created with ()?

I'm writing a script that starts a subshell to go off and do some work. In a special case, the script needs to tell the subshell to cleanly stop what it's doing and exit early. However, my ...
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Detect if a (NTFS) drive is mounted or not. If not then mount it

I want to sync an USB drive with a folder located on a NTFS partition which is not mounted at boot time. I have found a command to do that: rsync -axu /media/USB/folder /home/user/folder. But I have ...
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1answer
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Unix > overwrite command?

I'm doing a shell command (such as sh run.sh > log.txt). How do you overwrite the file each time (so each time I run it log.txt doesn't get appended) I'm doing this in a python script and I'm ...
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tar extraction depends on filename?

I often download tarballs with wget from sourceforge.net. The downloaded files then are named, e.g ...
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How to pipe output from one process to another but only execute if the first has output?

How can I rewrite this command to only email if there is output from the mailq | grep? mailq | egrep 'rejected|refused' -A 5 -B 5 | mail -s 'dd' email@email Is this even possible on one line?
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in zsh, how do I hide the backslashes in the completion menu

On Mac OS X 10.6, zsh. I have set in .zshrc: setopt automenu …to get a completion menu below the prompt. When I type: cd <TAB> I see a completion menu with all directories that have spaces ...
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Use HERE file and redirect output of command

I have the following code in a batch script: mpirun -np 6 ./laplace <<END 100 100 100 0.01 100 3 2 1 END | tail -n 1 > output But it isn't working. What I want it to do is to use the HERE ...
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2answers
292 views

Divorced input line in GNU Screen

Is it possible to divorce my input from the overall shell using Screen? What I'm aiming for is akin to a status line that expands if I type more than would fit within a single line and is ...
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Dollar sign interpolation inside quotes in bash

I am running this little test script I wrote : #!/bin/bash TESTCASE=$@ testHarness <<runTest $TESTCASE runTest from the command line : ./test.sh "1092$212" but the dollar sign is being ...
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1answer
229 views

sudo nt passing after redirection operator [duplicate]

Possible Duplicate: sudo permission denied but su grants permission I am trying to echo a new value into a file using following command sudo echo 4096 > /proc/sys/fs/file-max The ...
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2answers
787 views

writing a command transcript to file

Here is a script from Mercurial issue 2743. Call it mq.sh. I'm trying to get it to do the following things, on Debian squeeze. Echo commands + standard output + standard error to a file. Prefix with ...
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How do I temporarily bypass an alias in tcsh?

I am using tcsh. bash and zsh and other suggestions won't help here. I have several aliases that are named the same thing as another command, so if I did unalias it, typing the same thing would now ...
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How do i open all files that are the result of a ls command?

I'd like to open all text files that are the result of a ls command using a text editor. How do i do this?
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1answer
402 views

ftp and shebang

Is there a way to shebang-ify ftp and write small ftp scripts? For example: #!/usr/bin/ftp open 192.168.1.1 put *.gz quit Any thoughts?
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What does '//' mean in return from `which`

I have an executable script test under the full path /home/sawa/foo/bar/test. The directory /home/sawa/foo/bar is within $PATH, and has priority over the default ones including /usr/bin. When I do ...
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Intercept input and output from specific executable

I have a certain Linux executable that is called from a bigger application to perform some calculations. I want to modify the way the calculations are performed, for that I first need to understand ...
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How to run my C program from anywhere within the System (Ubuntu 10.10)?

Friends, I want to add my C program's path to the environment variable PATH. My C program called "md5". So that I can execute it from anywhere (i.e any directory). My md5 program is located at ...
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347 views

Can I have my shell history record how wildcards expanded?

If I run: $ ls * foo bar buzz $ history | tail -1 ls * You can see that in my shell history it remembers that I ran ls * rather than ls foo bar buzz. Ideally, I'd like to record both in separate ...
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checking an argument to a bash script is a string of all digits

The Bash FAQ says If you're validating a simple "string of digits", you can do it with a glob: # Bash if [[ $foo = *[!0-9]* ]]; then echo "'$foo' has a non-digit somewhere in it" else echo ...
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Is it possible in unix to search inside zip files

I have 100s of directories and within those I have a few zip files. Now there are images named abc.jpg in those zip files. The zip files may be in any folder or in any subfolder so its difficult to ...
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642 views

I'm confused as to why “| true” in a makefile has the same effect as “|| true”

I have a makefile where I'm stopping a service before removing a file. When it couldn't stop the service, it would break on error. This is clearly unwanted so I thought I'd add || true but missed a |. ...
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3answers
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How can I create multiple files in the current directory in bash?

Is there a command to create multiple files in the current directory? i.e. if I would like to create __init__.py, views.py, models.py and admin.py as follows: > COMMAND __init__.py views.py ...
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2answers
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How to diff a file and output from the command?

Normally you would write: diff file1 file2 But I would like to diff a file and output from the command (here I make command a trivial one): diff file1 <(cat file2 | sort) Ok, this work when I ...
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5answers
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How copy and rename files found in “find” function Linux?

I have a folder named /home/user/temps which has 487 folders. In each folder I have a file called thumb.png. I want to copy all files named thumb.png to a separate folder and rename them based on ...
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1answer
463 views

Single command to move a domain from cPanel's localdomains to remotedomains file?

I find myself needing to do this a few times daily and would love an easier way to do it. The domain example.com's email is handled by a third party, so the server needs to be told this by listing ...
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1answer
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Cron daemon error : Permission Denied

I am having trouble setting up a cron job. My set up is as follows: crontab -e */10 * * * * OTP_ProJect/PandaServerInfo/SVN/PandaQueueMonitoring/trunk/submit_cron_test.sh the shell script has ...
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Why the double quotes and backquotes in a shell script?

I'm looking at this script mysql backup script and I don't understand what is the reason for using both backticks and double quotes around command names? 379 WHICH="`which which`" 380 AWK="`${WHICH} ...
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3answers
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Print mac address to file

With a bash script, can I read the mac address of my eth0 and print it to a file?
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1answer
3k views

Grep - ^(\s*$) vs ^\s*$

I want to search for a field that only has spaces. When counting, this two commands gave me different results: grep "^\s*$" -E -c grep "^(\s*$)" -E -c Another thing. What is the correct way to say ...
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4answers
830 views

different shell for root and non-root user

When I ssh as root, my shell is bash, but when it's a non-root user it is sh. How can I make them both to use bash? This actually goes against the logic in this question: Why root's default shell is ...
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4answers
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What is the difference between a builtin command and one that is not?

Is there any intrinsic difference between a builtin command and another command which can nominally do the same thing? eg. Do builtins get "special" treatement? ... is there less overhead running ...
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Replacing text from a list of replacements. Added complication: backslashes

I have a file A that contains pairs of strings, one per line: \old1 \new1 \old2 \new2 ..... I would like to iterate over file A, and for each line perform the replacement (e.g. "\old1 -> \new1") ...
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Why is 'while.. read.. <<EOL' performing variable expansion, yet <file and | don't?

Aside from the variable expansion mentioned in the question's heading, I also experience another alarming issue when reading inline data to <<EOL... When the data contains a backtick `, it ...
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3answers
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What does “--” (double-dash) mean? (also known as “bare double dash”)

I have seen -- used in the compgen command. For example: compgen -W "foo bar baz" -- b What is the meaning of the --.
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2answers
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Generate suggestions for errors from a lookup dictionary

EDIT: the files were changed to tsv to deal better with spaces in text fields I have 2 csv files in the following form: File 1: availableText.csv (can be very big) "id1" , "text1-1" "id1" , ...
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2answers
374 views

Unix Shell and colours

Can any one please help me understand this code snippet that I found in .profile file echo -en "\e[32;44m $(hostname) \e[m";echo -e "\e[m"
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2answers
276 views

2 consecutive ssh logins [duplicate]

Possible Duplicate: Common multiple SSH connections file handling issue I used to do something like that often: home $> ssh user@server1 user@server1's password: server1 $> ssh ...
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1answer
10k views

How to assign values to multiple variables in command line with bars

I am essentially trying to assing certain portions of the output of a shell command to mulitple variables, but I don't know how to do that. For simplicity's sake, assume that the command on the ...
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11answers
3k views

Linux - command to list files (except ls)

Imagine you were working on a system and someone accidentally deleted the ls command (/bin/ls). How could you get a list of the files in the current directory? Try it. I tried many ...
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1answer
446 views

Multiple renaming files [duplicate]

Possible Duplicate: How to clean up file extensions? I'd like to rename files with extension .flac.mp3 to extension .mp3. I used the following command $ for i in *; do mv $i `echo $i | sed ...
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1answer
540 views

Execute file in its native directory with shell script

I'm executing a php file from the php-cli with a shell script. One of the php files creates a file named available_data during the course of its execution. The problem is that the php file needs to ...
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7answers
43k views

What's the difference between /sbin/nologin and /bin/false

Technically, unless pam is set up to check your shell with pam_shells neither of these can actually prevent your login, if you're not on the shell. On my system they are even different sizes, so I ...
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5answers
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Shell: How to read the bytes of a binary file and print as hexadecimal?

In shell, how can I read the bytes of a binary file I have, and print the output as hexadecimal numbers?
3
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1answer
395 views

Why does the rc.status file set the LC_ALL locale

I am currently creating a daemon service and in order to leverage existing service functionality, the startup script sources from /etc/status. This causes a problem with our service because within ...
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1answer
944 views

How to determine if disk is compact flash or standard hard drive

I need to determine in a shell script if a given block device (e.g. /dev/sda) is a compact flash disk or a regular hard drive. Google did not help me out for once, and while udevadm info --query=all ...
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4answers
30k views

Why is Debian's root shell colorless?

Are there any security concerns? What is the best way to enable it?
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How can I make scripts run when a file/directory changes in Linux (like Mac OS X’s launchd)? [duplicate]

Possible Duplicate: Can a bash script be hooked to a file? On Mac OS X, there’s a handy daemon called launchd which (amongst other things) allows you to have scripts run when files or ...
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1answer
182 views

Aliases for programs in /sbin/

I have a weird problem, unfortuantely I don't know what I did to cause this, since I tried out lots of stuff on my Linux (Archlinux, 2.6.38 kernel). The problem is: My shell is not finding programs in ...
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5answers
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Timing out in a shell script

I have a shell script that's reading from standard input. In rare circumstances, there will be no one ready to provide input, and the script must time out. In case of timeout, the script must execute ...
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1answer
6k views

How do I get which to show aliases? [duplicate]

Possible Duplicate: How to use which on an aliased command? I'm used to working on systems where which would list aliases, so e.g. if I have an alias like this: alias ...