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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12
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6answers
946 views

Why was the word “shell” used to descibe a command-line interface?

I'm curious about the term "shell." I think I know what it is (though the distinction between "shell" and "terminal" is still fuzzy) but why was the word "shell" chosen to describe this type of ...
3
votes
2answers
2k views

Is there a way to push shell config information when SSHing to a host?

I know how to set the GNOME-terminals (or xterms!) prompt to green/red regarding the last exit code: vi .bashrc export PROMPT_COMMAND='PS1="` if [[ \$? = "0" ]]; then echo "\\[\\033[0;32m\\]"; else ...
4
votes
3answers
577 views

mkdir based on input from other directories

I have a directory full of albums I've ripped to FLAC format. Folders are named "Artist - Album [flac]" I need to create matching directories named "Artist - Album [mp3]" but only for certain ...
10
votes
2answers
10k views

How to reset a shell environment?

This issue has been bugging me for a while, and although I've thought I've found my answer through EnvWatcher, unfortunately it only works on Bash. And I use zsh. I would like to replicate the things ...
4
votes
4answers
9k views

What is a command line alternative to top for finding current CPU utilization that isn't dependent on screen width?

If I run top -p <myPID> -n 1 with a terminal that isn't wide enough, the CPU utilization % is omitted from the output. When trying to find a process' cpu utilization via bash scripting, this is ...
2
votes
1answer
550 views

How do I make a droplet/.app in platypus for my unix command?

This is my sample code from the platypus tutorial. I am trying to make it work with a command named pymol, and I want it to open .pdb files or open just pymol. I know nothing about perl, but I have ...
4
votes
2answers
5k views

changing current working dir with a script

I've read this question and answer, but it doesn't quit fit my problem, even tho it's similar. I'm writing a script (called cpj) that will launch one of my current projects. I have about 5 of them. ...
4
votes
3answers
493 views

script to use the output of a command (ls) and use it in another command

I have a collection of pdf files I would like to convert to epub. I know Calibre's command ebook-convert will do the trick (nicely might I add). However I have more than one file. I'd like to be able ...
1
vote
4answers
358 views

Faster delayed execution than 1 minute?

I am working on a program that can "upgrade itself" by install a new package. In order to accomplish this, I am using the at command to specify that a shell script should be run one minute in the ...
0
votes
2answers
2k views

How to generate random IP addresses

$ nmap -n -iR 0 -sL > RANDOM-IPS-TMP.txt $ grep -o "[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*" RANDOM-IPS-TMP.txt | egrep -v "10.*|172.[16-32].*|192.168.*|[224-255].*" > RANDOM-IPS.txt egrep: Invalid ...
9
votes
2answers
8k views

How to make exported shell variables permanent?

export LD_PRELOAD=/usr/lib/libtsocks.so It's ok that I can export in this way, but how can I make it permanent? I want LD_PRELOAD to still be changed after a reboot. I'm using Ubuntu and Fedora
1
vote
1answer
371 views

Which process/program create/write the file which I/O is redirected to?

When learning SELinux, I executed semanage fcontext -l > fcontext.txt under /root directory to dump massive fcontext information to a file. The funny result is: fcontext.txt was created, but the ...
3
votes
1answer
543 views

Git - remove deleted files

I'm using this simple git alias rmdel = "!git rm $(git ls-files -d)" meant "remove deleted", i.e. to remove from the staging area all files deleted from the file system. It works fine except ...
90
votes
13answers
37k views

Get exit status of process that's piped to another

I have two processes foo and bar, connected with a pipe: $ foo | bar bar always exits 0; I'm interested in the exit code of foo. Is there any way to get at it?
3
votes
2answers
828 views

Cut on both characters and field

I have a record like : 2011-05-29 17:51:34 => 'HS|CMGC|RN431|CI13950|CH7-4a37-afe2-acabfc9d262d|DA110529|TI175133|' I want my final output to be something like: 2011-05-29 17:51:34 CI13950 I ...
2
votes
2answers
2k views

How to remove the directory a symbolic link links to plus the symbolic link?

Say a is a symbolic link to b. I am looking for a simple command to remove both a and b at once that does not require me to know about b.
8
votes
2answers
660 views

zsh tab completion on empty line

I'd like a tcsh'ism that I haven't been able to find: On a blank line with no content, I want to press the tab key and see the equivalent of an ls. That is to say I want $ <tab> to do ...
3
votes
2answers
193 views

returning strings corresponding to shell glob matching

Suppose I have a subdirectory called sub. Then I want to operate on all files in that directory with the extension "txt". I want something like for f in sub/*.txt do enscript -b "" -o {$f ...
7
votes
3answers
467 views

“mkdir foo; svn mv * foo”

I often want to do some variant of this idiom: $ mkdir 2010 $ svn mv * 2010 Of course, I get an error because the glob matches 2010 as well: svn: Cannot copy path '2010' into its own child ...
1
vote
1answer
3k views

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 ...
5
votes
4answers
4k views

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 ...
0
votes
1answer
3k views

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 ...
11
votes
4answers
5k views

tar extraction depends on filename?

I often download tarballs with wget from sourceforge.net. The downloaded files then are named, e.g ...
16
votes
8answers
5k views

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?
7
votes
1answer
306 views

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 ...
10
votes
2answers
3k views

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 ...
3
votes
2answers
301 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 ...
5
votes
1answer
5k views

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 ...
0
votes
1answer
241 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 ...
1
vote
2answers
867 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 ...
10
votes
2answers
4k views

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 ...
7
votes
3answers
4k views

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?
7
votes
1answer
448 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?
4
votes
2answers
790 views

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 ...
4
votes
3answers
2k views

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 ...
1
vote
4answers
1k views

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 ...
6
votes
1answer
360 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 ...
4
votes
3answers
10k views

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 ...
5
votes
4answers
5k views

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 ...
9
votes
1answer
764 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 |. ...
2
votes
3answers
1k views

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 ...
13
votes
2answers
5k views

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 ...
7
votes
5answers
19k views

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 ...
2
votes
1answer
511 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 ...
2
votes
1answer
2k views

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 ...
5
votes
3answers
4k views

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} ...
6
votes
3answers
2k views

Print mac address to file

With a bash script, can I read the mac address of my eth0 and print it to a file?
3
votes
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 ...
2
votes
4answers
1k 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 ...
35
votes
4answers
5k views

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 ...