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, …).

learn more… | top users | synonyms (1)

0
votes
1answer
14 views

How to spawn new processes for new instances of the same shell script?

I'm trying to lock a file using the command lock. It's syntax is ./lock </path/to/file/name> I need to lock a bunch of files in a given directory and in order to achieve this I'm using two ...
0
votes
1answer
33 views

How to pass arguments to a Java process from within a shell script [on hold]

This may be a duplicate but the initial questions I have found did not resolve the issue. We have a script which calls a java process with arguments, one of the arguments has spaces in it. When ...
18
votes
6answers
67k views

How can I read line by line from a variable in bash?

I have a variable which contains multiline output of a command. What's the most effecient way to read the output line by line from the variable? For example: jobs="$(jobs)" if [ "$jobs" ]; then ...
7
votes
2answers
11k views

Running chsh does not change shell

I want to change my shell from bash to zsh. I have tried running the following while logged in as user zol: $ chsh -s /bin/zsh $ sudo chsh -s /bin/zsh zol $ su -c 'chsh -s /bin/zsh zol' # The above ...
1
vote
2answers
43 views

How to use ln -s to create a command line shortcut?

I have an sh file that I would like to be able to open from the terminal at any time. I would like to type "studio" into the terminal, and have android studio open I recall using ln -s to do this, ...
1
vote
1answer
20 views

Pass shell variables to SQL statement

I want to pass shell variables to sql statement. Both shell script and SQL statement are present in the same script file. I want the values of the variables retMonth, retLastDay and retPrvYear in the ...
12
votes
2answers
419 views

What does CTRL+4 (and CTRL+\) do in bash?

I just found out by accident that CTRL + 4 closes programs reading stdin input from the command-line. This is how it looks when I type CTRL + 4 or CTRL + / into programs reading stdin ryvnf:~$ ...
-1
votes
0answers
13 views

Debian Linux Shell has no colors and desktop files/folders gone GNOME

Hello I have installed some packages to fix sound mute, but instead, after restart I saw no icons on desktop except 'Computer'. I have opened shell and wanted to do apt-get update but saw that the ...
7
votes
4answers
2k views

How to get mount point of filesystem containing given file

I am looking for a quick way to find the mount point of the file system containing a given FILE. Is there anything simpler or more direct than my solution below? df -h FILE |tail -1 | awk -F% ...
1
vote
1answer
17 views

What files were sourced, zsh

I use oh-my-zsh with zpretzo, and I keep forgetting the zsh files it sources that I want to edit. How can I ask the shell what source files it sourced?
19
votes
4answers
31k views

Testing if a variable is empty in a shell script

I have seen the following technique used many times on many different shells, to test if a variable is empty: if [ "x$1" = "x" ]; then # Variable is empty fi Are there any advantages on using ...
1
vote
2answers
62 views

Need output in a good format using shell script

I have a file, PoolReport.txt. Here is some sample data: Thu, Aug 27, 2015 7:56:29 AM PoolName,Total GB,Used GB ,Available GB ,Percent Full Oracle-RAID10,6432.539,6179.295,253.244,96.063 ...
4
votes
4answers
337 views

$@ except the 1st argument

I need to write a shell script that runs in this way: ./myscript arg1 arg2_1 arg2_2 arg2_3 ....... arg2_# there is a for loop inside script for i in $@ However, as I know, $@ includes $1 up to ...
0
votes
3answers
42 views

Rename files in directory according to name of directory

I am trying to rename a bunch of files according to the names of their directory in Linux, SSH. I have a directory called XYZ01smith. In it are four files called smith_5*.I need to add prefix XYZ01 ...
-3
votes
1answer
42 views

How can i replace a specific string within a line inside a text file [duplicate]

$ cat text.txt my name is Steven my age is 10 i like dogs What command will be fitting so that echo "Kate" will replace Steven on text.txt?
2
votes
3answers
31 views

echo and command substitution

I wrote a very basic script of command substitution which is below: #!/bin/bash files=$(ls *.fastq); echo $files The directory contains bunch of .fastq file and I just want to use echo command to ...
1
vote
1answer
25 views

Check if multiple files exist in directory

How to find multiple files present in a directory in ksh (on AIX) I am trying below one: if [ $# -lt 1 ];then echo "Please enter the path" exit fi path=$1 if [ [ ! f $path/cc*.csv ] ...
2
votes
2answers
209 views

Setting environment variables with .bash_profile: only last export works properly

I am trying to export some environment variables in Unix using .bash_profile It reads now like this: export PATH=${PATH}:/usr/local/cuda-6.0/bin/ export ...
6
votes
3answers
600 views

bash: escape individual lines from `-x` echoing

In bash, when running with the -x option, is it possible to exempt individual commands from echoing? I'm trying to make the output as neat as possible, so I am running certain parts of my script in a ...
0
votes
0answers
27 views

How do I send a variable through SSH so it can be used across servers? C Shell

EDIT: Would this be possible in bash? Note: I have to use C shell. (.csh) I have something very similar to the following code: set var = "string" ssh -X server "$var" << END * I ...
0
votes
1answer
30 views

Big XML - copy data from nth Occurrences to another file

<XML> <Employee> <firstname></firstname><lastname></lastname> </Employee> <Employee> ...
9
votes
2answers
392 views

How does a shell execute a program?

If I compile a program using gcc, and try to execute it from the bash shell, what is the exact sequence of steps followed by bash to execute it ? I know fork(), execve(), loader, dynamic linker (and ...
2
votes
2answers
57 views

List transient files by numerical value having number greater than a given constantly varying filename

I've a directory having constantly changing filenames (by numerical value) listed as: -rw-rw----. 1 root root 10493952 May 7 10:39 A0000000.LOG -rw-rw----. 1 root root 10493952 May 7 08:38 ...
1
vote
1answer
18 views

adb pull not accepting a variable as source, gives *' does not exist..* error

I'm trying to use $EXTERNAL_STORAGE in the adb pull command. I noticed that the variable has its scope defined in Android only and so it would not work successfully in adb pull ...
2
votes
2answers
35 views

automating CentOS 7 configuration using shell scripts

I notice I spend a lot of time using tutorials to manually configure a CentOS 7 server. How can I convert the manual steps from a tutorial into an automated shell script that can be used to configure ...
19
votes
9answers
3k views

Grep lines but let the first line through [duplicate]

Consider the following output from df. Filesystem Size Used Avail Use% Mounted on /dev/sda1 23G 6.1G 16G 29% / udev 10M 0 10M 0% /dev tmpfs 397M 420K ...
8
votes
3answers
34k views

How can I delete all files with a particular extension in a particular folder?

If I set the current/working directory (navigating to it using cd) to some particular directory and then type: rm *.xvg What will this command do? Is it true that the above command will only ...
1
vote
0answers
7 views

Global [multiple sessions] directory stack

For the current zsh session I use dirs -v command to print the directory stack. I'd like to have an analogous tool that shows me the directory stack of all sessions, also the closed ones. Or if not a ...
31
votes
2answers
27k views

How to remove a single line from history?

I'm working in Mac OSX, so I guess I'm using bash...? Sometimes I enter something that I don't want to be remembered in the history. How do I remove it?
18
votes
6answers
1k views

How can I cleanly add to $PATH?

I'd like a way to add things to $PATH, system-wide or for an individual user, without potentially adding the same path multiple times. One reason to want to do this is so that additions can be made ...
6
votes
4answers
5k views

How to use a variable as part of an array name

I have two arrays: arrayA=(1 2 3) arrayB=(a b c) and I want to print out one of them using a command line argument, i.e., without any if else. I tried a few variations on the syntax with no ...
0
votes
1answer
41 views

Silently timeout command in zsh

This is an oft-asked question: Superuser/loop-start-program-and-kill-after-time-out SO/bash-script-that-kills-a-child-process-after-a-given-timeout SO/bash-run-a-process-for-limited-time-period ...
1
vote
1answer
43 views

How to print the line numbers with corresponding line that matches a pattern using shell command? [duplicate]

File, .false alarm is bla no. 11 .no alarm generated is bla .application will be killed is bla wall command .doc file is document file with .doc extension .no authority for this selection bla Now ...
12
votes
4answers
375 views

Why does cat x >> x loop?

The following bash commands go into an infinte loop: $ echo hi > x $ cat x >> x I can guess that cat continues to read from x after it has started writing to stdout. What is confusing, ...
0
votes
2answers
37 views

How to store whole a paragraph as one element of array in bash script

I am using the following code to read data from a file abcd.txt and try to store in an array parameters, I am able to store 619617 in parameter[0] and update in parameters[1] but in parameters[2] I am ...
0
votes
1answer
36 views

Scripts in rc.local (start at boot), doesnot start

In my Debian /etc/rc.local, I've put 2 scripts (one for Wifi AP, the other for VPN client-connection): sh /bootscripts/vpn.sh & sh /bootscripts/wifiap.sh & #test: date >> ...
-2
votes
3answers
440 views

find command and tar

find /informatica/dev/SrcFiles* -mtime +7 -and -size +1M -exec tar -cvjf> So I ran this command and I can't find the file after it was done running (probably because I never named it?). The ...
1
vote
2answers
62 views

Cron only occasionally sends e-mail on output and errors

On Debian 8.1, I'm using a Bash feature to detect whether the stackoverflow.com website is reachable: (echo >/dev/tcp/stackoverflow.com/80) &>/dev/null || echo "stackoverflow unreachable" This is ...
2
votes
1answer
286 views

alias -g '${1+“$@”}'='“$@”', what does it do?

Most makefile have this strange set of symbols '${1+"$@"}'. $@ is the makefile target filename. But why does, people try to use the complex symbol like '${1+"$@"}'?
0
votes
1answer
22 views

sed command to delete variable number of lines

To delete the first 10 lines from a text file, the following command is used: sed -i -e "1,10d" filename what if I want to delete n number of lines, where n is a variable. i.e. I am using ...
1
vote
2answers
49 views

Escaping a linux command

I'm trying to run a command from a script I wrote that basically replaces a string in file vzctl exec VZID sed -i 's/\/>/address="$IP\/255.255.255.0"\/\>/' "file.xml" The problem is the ...
0
votes
1answer
29 views

DNS Query Script

I am trying to get all the A records for some domains. The best way I have found is to use https://www.whatsmydns.net and the nexcess tool. The issue is that it is very slow to copy paste them and ...
0
votes
1answer
16 views

Is there a GUI debugger for csh script?

I have read another question in UNIX & LINUX stack exchange. The GUI provided in that question can be used to bebug *.sh file. How about to debug *.csh file? What other plugins for eclipse can I ...
0
votes
0answers
11 views

Zenity. How to run as an application?

I built a script (bash), then I overlaid it with Zenity (to have a progressbar in a GUI for non linuxian users). How can I deliver it as an app, not a .sh ? And never show a square of terminal ?
3
votes
2answers
136 views

Which shells don't support dollar-parenthesis expansion, and demand backticks?

The modern recommendation is to use: $(...) instead of the older: `...` mainly for readability and to avoid the need for escaping when nesting. Which shells do not support the $(...) form, and ...
11
votes
5answers
15k views

Generate random numbers in specific range

After googling a bit I couldn't find a simple way to generate with a shell command a random number included in a specific range, between a minimum and a maximum. I read about /dev/random, ...
25
votes
12answers
9k views

Object-oriented shell for *nix

Preface: I love bash and have no intention of starting any sort of argument or holy-war, and hopefully this is not an extremely naive question. This question is somewhat related to this post on ...
0
votes
1answer
20 views

Running repetitive task through Bash script

I'm running a few repetitive tasks and I think will be good to create a small bash script to perform all them in just one command: run the bash script. This are the tasks I need to run: # stop HTTPD, ...
-1
votes
0answers
25 views

Shell Script Flashing [closed]

I created my first shell script. It's an audio logger that runs on the hour for an hour and restarts. Although if it is started within the hour it will only run until the end of the hour. I've added ...
0
votes
4answers
72 views

How can I test for the .RAW file extension?

I'm trying to set up an sh script that will run every 30 minutes. During each run, I want to check a directory for the presence of at least one .RAW file. Upon finding that file extension, I will have ...