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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2
votes
1answer
409 views

KSH styling text based menu using STDERR

Is it possible to format the STDERR in order to have a better looking menu using the select command? I have a simple select select oChoice in $(<tempMenu.menu) ; do case "$oChoice" in ...
1
vote
1answer
27 views

Can I start a background process with a specific working directory?

Say I have this structure /masterscript /a/script1 /a/b/script2 In masterscript I spawn the other scripts as background processes: "/a/script1" & "/a/b/script2" & The problem is that ...
1
vote
1answer
32 views

Running shell script on cluster in parralel

I thought dsh(Distributed Shel) will be a good option but when i ran my shell script across my nodes, I didnt get expected output, dsh -aM -c bash /home/cloudera/bash_script.sh server2@x.x.x.110: ...
18
votes
1answer
13k views

How to loop over the lines of a file?

Say I have this file: hello world hello world This program #!/bin/bash for i in $(cat $1); do echo "tester: $i" done outputs tester: hello tester: world tester: hello tester: world I'd ...
2
votes
1answer
16 views

How to sort files based on the json property value inside the file?

I've downloaded list of videos via youtube-dl and each file has corresponding .json file containing certain properties. So I would like to sort the files based on the selected json property which is ...
1
vote
1answer
673 views

Deleting Non-empty Directory with smbclient

How can I remove a non-empty directory with smbclient? I have tried the following: 1) rm Result: NT_STATUS_NO_SUCH_FILE listing [dir_path] 2) recurse;rm Result: No Error but also nothing ...
0
votes
1answer
7 views

How to automate ktutil to immediately list keytab entries?

I use MIT ktutil a lot on Linux and I am fed up using the following sequence, even if command shortcuts and file name completion are here to help: ktutil rkt my.keytab l Isn't there a way to get ...
5
votes
3answers
257 views

cd to directory of a symbolically linked file

Before I write a script, anyone know an easy way to do the following: $ pwd /foo/bar $ ls -l lrwxr-xr-x 1 username admin 48 Apr 17 2012 foo.sh -> /bar/foo.sh $ cd /bar $ ls foo.sh i.e., in ...
6
votes
2answers
143 views

Bash string concatenation used to build parameter list

Given this piece of bash: PARMS='-rvu' PARMS+=" --delete --exclude='.git'" echo $PARMS rsync ${PARMS} . ${TARGET} The echo shows the PARMS string as expected, no error is displayed, but rsync ...
6
votes
2answers
248 views

Why does source give an error “cannot execute binary file”

I have small file that does initialize a tmux session and then creates some windows. After some debugging and tweaking things worked fine until I renamed the text file (with the tmux commands) from ...
1
vote
2answers
75 views

I want to suppress “no access to tty” error message?

I have a bash script where I use ssh to connect to another server and run some commands there. I found some sites that the error (Warning: no access to tty (Bad file descriptor). Thus no job control ...
1
vote
0answers
43 views

How to start a process chain from the shell

Is it possible and if so how do I: Start a /bin/bash process that is not bound to a terminal from a terminal? Hence, a shell process that shows up in the process tree as init -- bash. (Shells ...
1
vote
1answer
35 views

Apply given rsync exclude patterns on given directory

I have a setup where I use rsync to mirror some source directory to a (remote) destination except for some files and locations defined witch rsync exclude patterns: # Useless files - thumbs.db - *.~ ...
2
votes
0answers
49 views

How can you get the current terminal line (the one that is still editable by the user)?

I need a way to use the current line which the users typed into as variable for a shell function. my current code, which can be called by ctrl+r zle -N search bindkey "^R" search search () { read ...
1
vote
2answers
85 views

Login by ssh , exec one command and i don't want to quit the bash

I want to change PS1 when i ssh another centos strshell = 'PS1="remote!"' os.system("ssh -i %s -l%s -p%s %s %s"%(SSH_KEY,SSH_USER,SSH_PORT,des,strshell)) ssh quit automatically. I want to ...
17
votes
3answers
697 views

What are the responsibilities of each Pseudo-Terminal (PTY) component (software, master side, slave side)?

I am trying to figure out how a tty works1 (the work-flow and responsibilities of each elements). I have read several interesting articles about it, but there are still some blurry areas. This is ...
8
votes
1answer
133 views

How to “correctly” start an application from a shell

I find it hard to phrase the question precisely but I will give my best. I use dwm as my default window manager and dmenu as my application launcher. I hardly use GUI applications aside from my ...
1
vote
2answers
35 views

Passing print pattern as a variable to awk

I am trying to use awk to print variables from various columns in a line delimited by , .The columns and pattern which I want to print is stored in another variable b. The pattern a and print patter ...
1
vote
1answer
114 views

Pattern replacement

Please can anyone explain to me in brief the syntax of this command. Explanation in terms of how actually this command is written significance of each and every character used. I know the output of ...
2
votes
2answers
42 views

How do you get a count of all file extensions on a hard drive using the gnu+linux terminal?

On windows I have a program that can count all the files on a hard drive and the output shows a list of file extensions and a number (which showed how many files on the drive were for example are ...
4
votes
2answers
5k views

How to list ALL directories according to their size? [without including the parent directory]

I have a bunch of random folders, some of them are hidden (beginning with a period). I want to list all of them, sorted by their sizes. I have something on the lines of this in mind: ls -d -1 -a */ ...
2
votes
3answers
137 views

Saving individual output lines into variables

I'm using find -mtime -2 to find files modified in the past 24 hours or less. The output looks like this. /home/user/logs/file-2014-08-22.log /home/user/logs/file-2014-08-23.log I need to save the ...
5
votes
2answers
433 views

Is there any way to read lines from command output?

I have a pre process command to output a file ./preprocess.sh > preprocessed_file and the preprocessed_file will be used like this while read line do ./research.sh $line & done < ...
-2
votes
0answers
16 views

Explain a tsums command line

In putty, I am blindly writing codes as below, cat >! lot tsums @lot -format=lot,machine_id > ! MCID what is the meaning of these 2 lines?
1
vote
2answers
59 views

Confusions mitigation while working similar environments in multiple servers

I often have to open multiple ssh sell terminals of remote servers together., eg. Dev and test. These paths and applications are exactly similar. And I am often confused if I run a particular command ...
5
votes
2answers
888 views

How to download an archive and extract it without saving the archive to disk?

I'd like to download, and extract an archive under a given directory. Here is how I've been doing it so far: wget http://downloads.mysql.com/source/dbt2-0.37.50.3.tar.gz tar zxf dbt2-0.37.50.3.tar.gz ...
3
votes
4answers
146 views

gunzip a folder with many files

I have a folder with 36,348 files gz files. I want to unzip all of them. Running: gunzip ./* results in -bash: /usr/bin/gunzip: Argument list too long Whats the easiest way to get around ...
18
votes
4answers
738 views

Why doesn't the tilde (~) expand inside double quotes?

According to this answer and my own understanding, the tilde expands to the home directory: ➜ ~ echo ~ /home/braiam Now, whenever I want the shell expansion to work, i. e. using variable names ...
2
votes
1answer
134 views

Syntax error near unexpected token `('

When I use below code in SSH terminal for CentOS it works fine: paste <(printf "%s\n" "TOP") But if I place the same line code in a shell script (test.sh) and run shell script from terminal, it ...
10
votes
6answers
7k views

How can I switch between different audio output hardware using the shell?

I use my laptop with an external monitor which has speakers. When the monitor is attached through HDMI I can switch (using the GUI: Sound Setting --> Hardware) between the normal laptop audio output ...
2
votes
1answer
187 views

Running sh script: «Permission denied» despite the executable bit and root rights

I installed Debian in VirtualBox (for various experiments which usually broke my system) and tried to launch the VirtualBox guest addon script. I logged in as root and tried to launch autorun.sh, but ...
-2
votes
0answers
29 views

How do you match an arbitrary ratio of words of a certain length(such as one out of two words of at least 4 chars) with a regular expression?

Considering formatted text and using shell utilities, how would you match: All numerical strings and; For each line, for words containing 4 characters or more (à la strings) n word(s) out of every ...
6
votes
1answer
347 views

Expand ~, . and `..`

Since ~, . and .. are special directories, why are they handled differently in the following example? $ echo ~ /home/tim $ echo .. .. $ echo . . ~ is expanded into the dir, but the other two are ...
2
votes
1answer
17 views

ionCube shell script gives error

I have this shell script to install ionCube loader: if [[ $(id -u) -ne 0 ]] ; then echo "Please run as root" ; exit 1 ; fi echo "Welcome to this script to install the ionCube loader on CentOS!" cd ...
5
votes
1answer
22 views

Upstart and bash function names containing “-”

I inherited some bash scripts where the author used "-" in the function names instead of the more normal "_" e.g.: function a-b { ... } Ugly but legal in bash. Problem is I sourced this inside an ...
1
vote
2answers
36 views

How do I find a files directory?

I am looking for a specific file in OS/X. I can see the file by using: ls -alR | grep "mkmf.*" This shows my that the file exists. How do I find what directory the file is located. Many thanks ...
1
vote
3answers
1k views

How can I run a “grep | grep” command as a string in a bash function?

I'm trying to build a command that pipes the results of one grep command to another grep command in a bash function. Ultimately, I want the command executed to look like this: grep -I -r FooBar ...
6
votes
6answers
220 views

Obtain values of a section of a file

I have a configuration file in the following format. <Title> [part1] A.File = a A.Val = val1 B.File = a B.Val = val1 [part2] A.File = a1 A.Val = val2 B.File = a B.Val = val1 ...
2
votes
1answer
18 views

Comparison of columns in two files and appending the first file

I need a help on this :- I have a file : emp.txt 21356 suresh 12/12/2012 23511 ramesh 11/06/2011 31456 biswajit 09/08/2013 53134 archan 06/02/2009 first field:- employee id, 2nd field is name and ...
13
votes
0answers
756 views

What does “mv *” do? [duplicate]

I just gave this command by accident mv * while I was in a directory, needless to say that the content of my dir is gone and I have almost no hope to recover it, luckily it wasn't something ...
2
votes
2answers
142 views

creating variable using variable value as part of new variable name

I'm trying to create a new variable using the value of an existing variable as part of the variable name. filemsg"$word1"=" " I've also tried filemsg$word1=" " filemsg${word1}=" " on all ...
2
votes
1answer
36 views

Read target of symlink and increment target by one

I have a folder structure that looks like this /some/folder/1 /some/folder/2 ... and a symlink current that links to one of the folders. Is it possible and when how to read the target of the link, ...
1
vote
3answers
47 views

How to send a output of unix command from one server to another server?

How to redirect the output of a unix command from one server to another server. I should be able to send the unix command's output from server-1. Then I should be able to receive the output in ...
4
votes
2answers
64 views

How do I cancel/replace one element of running `cmd1 && cmd2 && cmd3 && …` chain?

$ command1 && command2 && command3 Running command1 ... Running command2 ...^Z [1]+ Stopped $ fg && command4 && wrong_command5 && command6 Running command3 ...
8
votes
1answer
14k views

How to check if there are no parameters provided to a command?

How do you check if $* is empty? In other words, how to check if there were no arguments provided to a command?
0
votes
2answers
33 views

How to set cron job for system

I'm really new on Linux and have no any previous experience on it. And I opened this account to ask this question. I need to install a cron job I've followed the short guide here. Well, I think it ...
2
votes
2answers
632 views

Using sudoers to allow php to run command

I am trying to get my php page to run this command: shell_exec("sudo /home/xbian/433Utils/RPi_utils/codesend {$num}"); So I added this entry to my sudoers file with visudo: www-data ALL=NOPASSWD: ...
1
vote
3answers
46 views

How to handle backspace while reading?

How do I handle the backspaces entered, it shows ^? if tried & how read counts the characters, as in 12^?3 already 5 characters were complete(though all of them were not actual input), but after ...
3
votes
4answers
156 views

Redirect and pipe output

rpm -qa > file | wc -l returns 0. What am I doing wrong? I think it is clear what my goal is, but it isn't working. Is this a job for xargs or tee?
1
vote
3answers
43 views

bash/shell pathname expansion for mkdir, touch etc?

So doing something like this in bash and most other shells won't work to create multiple subdirectories or files within subdirectories... mkdir */test touch */hello.txt There are of course many ...