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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How to get started with bash? [closed]

I need a way to be able to run a script that will automate terminal commands, one after another. As I understand it, this is exactly what bash does. (Am I right, even on this count?) Where can I ...
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1answer
3k views

How I append the data of Multiple files into one file?

I want to append data of approx 500 files into one file and each of these files are located in their respective dirs. Also How i can verify the contents of merged file e.g How i verify that data ...
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1answer
104 views

How to measure rlogin time?

I need to monitor the time it takes to rlogin from one HP-UX machine to another. So I wrote this: #!/bin/sh result=`rlogin 10.10.10.1 << EOF exit EOF` result2=`{ time $result >/dev/null; } |...
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1answer
431 views

indirect variable expansion in POSIX as done in bash? [closed]

Is it possible, or is there some elegant hack to do indirect variable expansion in POSIX as can be done in Bash? For context, I'm trying to do the following: for key in ${!map_*} do # do ...
2
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2answers
325 views

How to split files with common prefix in bash

I have a directory with many files with common prefix, like gsc*_other.foo, where * is a character that goes from 0 to 9 or a/b (where a stands for 10 and b for 11). My goal is to create text files ...
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2answers
19k views

Mysql query resultset in bash script

I am using the bash script to connect to the mysql database and execute a query. I use the below script to connect to the database and execute the query. #!/bin/bash Total_Results=$(mysql -h ...
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2answers
5k views

Save find -exec output to text file

I have a set of videos in the folder. I would like to get the info about this videos using ffmpeg -i command and save the output to file. So I wrote the line: find . -type f -exec ffmpeg -i {} \; &...
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1answer
52 views

Timestamp ts not working with thinkfan

I wanted the output of thinkfan -n output with a timestamp next to it so I can later analyse the patterns, and found this question: Prepending a timestamp to each line of output from a command, which ...
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3answers
37 views

Move line from output to the front of output or custom reordering

I have a command find "$PWD" -name __openerp__.py|awk -F/ -vOFS=/ 'NF-=2'|sort -u and I want to take a certain line containing /web/addons and push it to the front of output then do the same with /...
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1answer
3k views

How to execute Netscaler commands through a remote machine via SSH connection

I have been trying to execute some NetScaler commands like "bind" & "unbind" through a Linux Box via an SSH Connection. Now the Problem is, Manually we are able to enter & execute commands on ...
2
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4answers
921 views

print parent directories full path of find output

what I want to do is to find all files based on some search query and get parents parent directory (../..) full path. For example find . -name "__openerp__.py" and then for each file execute ...
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1answer
215 views

Program acting differently depending on user

I am trying to control an RC transmitter from a PHP site. The command works fine as user "xbian" in the command line: sudo /home/xbian/433Utils/RPi_utils/codesend 34832404 for example, and it works ...
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2answers
1k views

How to detect aspect ratio of monitor?

How do you detect the aspect ratio of your monitor? I tried: root@malou-laptop:/home/liv# xrandr -q xrandr: Failed to get size of gamma for output default Screen 0: minimum 640 x 480, current 1680 x ...
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2answers
16k views

How to change default shell to ZSH - chsh says “invalid shell”

I installed ZSH on a VM of mine, where I compiled it from source. The location of ZSH is /usr/local/bin/zsh when I run chsh -s /usr/local/bin/zsh it outputs chsh: /usr/local/bin/zsh is an invalid ...
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3answers
493 views

running an executable in parallel by dividing the input directory tree

Commands like find and grep would benefit greatly if they were to run in parallel. Is there a utility or a program that takes a command as an argument and makes it run in parallel by running multiple ...
3
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1answer
121 views

Evolution of the shell [duplicate]

I've been doing some shell scripting. It always gives me a headache. Clearly this language has evolved organically, much as real life languages; new constructs have been dynamically added, ...
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3answers
487 views

I need data from a csv file which is not present in the second csv file

For example: I have a CSV file (first file ) with below data (vertically): 1 2 3 4 5 6 Second CSV with below data (vertically): 5 6 7 8 I want my resultant file (action needs to be performed ...
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2answers
961 views

Is CDPATH behavior broken in bourne shell (/bin/sh)

I have the following script: #!/bin/sh mkdir -p /tmp/test/foo cd /tmp/test unset CDPATH echo "TEST1: Current working directory: ${PWD}" echo "TEST1: attempting to 'cd foo'" cd foo echo "TEST1: ...
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7answers
8k views

Using notify-send with cron

I am using Arch Linux with KDE/Awesome WM. I am trying to get notify-send to work with cron. I have tried setting DISPLAY/XAUTHORITY variables, and running notify-send with "sudo -u", all without ...
4
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1answer
698 views

How to execute a Bash comand and execute two statements on failure?

Ì want to execute a Bash command, followed by two actions if and only if the test returns an error. I would prefer to solve this task as a one-liner in Bash. Here are the two forms I have tried: ...
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5answers
3k views

How does one find out how many bits a file has in one command?

I know I can use ls -lat to find out how many bytes has a file and then multiply by 8 to find out how many bits. But is this possible in only one command line?
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1answer
729 views

how to send keyboard signal using a shell script

I have an application in graphical interface that when I run it, it's not opened in full screen mode, but when I use the keyboard shortcut Alt+Ctrl+M , it becomes fullscreen, I want to change the ...
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1answer
6k views

Meaning of `export PATH=…` in .bash_profile

I'm using a mac for some years now and as I'm currently learning ruby on rails, I felt like I should learn more about the system I'm using. I took a look at the ~/.bash_profile, it looks like this ...
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1answer
370 views

Getting tree command to not display directories

I've read through the man pages for tree but I don't know if it is possible to have tree list only the filenames for all files that appear in any recursive search of a directory. The closest I have ...
1
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1answer
209 views

Unknown syntax in /etc/rc.d/init.d/functions

Looking at the file /etc/rc.d/init.d/functions, I can see the following is declaring a number of variables as local variables. However, why are the variables killlevel and pid_file have an equal sign ...
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3answers
3k 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: /...
4
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1answer
366 views

How can I configure ZSH's vi mode to persist the state between commands?

I am aware how to set ZSH's default line editor to use vi-like keybindings... bindkeys -v ...and even to default each new prompt to be in command mode instead of insert mod by default... zle-line-...
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2answers
6k views

What is the difference between “du -sh *” and “du -sh ./*”?

The title says it all. What's the difference between those 2 commands? NOTE: I'm more interested in the * and ./* part.
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3answers
209 views

Environment variable for command called via nice

I need to set an environment variable for a command that is being called via nice. [Bash and dash, Slackware and FreeBSD.] $ JIM=20 nice -n 10 echo $JIM $ Nope, echo can't see JIM $ nice -n ...
6
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1answer
781 views

Bash is automatically reloading (injecting) updates into a running script upon saving it: Why? Any practical use?

I was writing a bash script, and happened to updated the code (saved the script file to disk) while the script was waiting for some input in a while loop. After I returned to the terminal and ...
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3answers
7k views

Select lines from text file which have ids listed in another file

I use a lot of grep awk sort in my unix shell to work with medium-sized (around 10M-100M lines) tab-separated column text files. In this respect unix shell is my spreadsheet. But I have one huge ...
3
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1answer
207 views

How can the order of execution in the shell as it relates to redirection be upset about 1 time out of a 1000 on my system? [duplicate]

Considering this Q&A about the order of execution in the shell as it relates to redirection, and despite the fact that if a file doesn't exist it gets created first so that cat example.txt | shuf &...
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5answers
3k views

Why does the command shuf file > file leave an empty file, but similar commands do not?

I know this is sort of a duplicate of another question (Why this sort command gives me an empty file?) but I wanted to expand on the question in response to the answers given. The command shuf ...
0
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1answer
56 views

Error in Dansguardian init.d sh script?

In the Dansguardian init.d script there is a function involved in shutdown that looks like: #!/bin/sh wait_for_pid() { local PID=$1 local RET=0 if [ $PID -eq 0 ] ; then return $RET fi # give ...
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5answers
1k views

How to copy 5 newest files from one directory to another and delete the old copies

How can I copy the 5 newest files from a directory to another in a "new to old" order.
19
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2answers
31k views

Why does Ctrl-D (EOF) exit the shell?

Are you literally "ending a file" by inputting this escape sequence, i.e. is the interactive shell session is seen as a real file stream by the shell, like any other file stream? If so, which file? ...
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3answers
3k views

bash adds extra single quotes

I have a problem executing my script. When executing it in debug mode (bash -x), I can see that bash is adding extra quotes. Therefor my script is failing. Here this is within my script: testvar="\...
3
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1answer
131 views

How does one determine the amount of space allocated to their command line?

How would one go about determining the amount of space allocated to their system for command lines. Is there anything else I need to be concerned with?
3
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2answers
448 views

How do you preserve a space in a literal expression in an array value in bash and how to trim down results from a sort command?

In the context of searching for expressions in log files, I was wondering generally if there was a way to quantify and qualify the contents of the logs in /var/log in some way. In particular, does the ...
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5answers
4k views

Using a generated list of filenames as argument list — with spaces

I'm trying to invoke a script with a list of filenames collected by find. Nothing special, just someting like this: $ myscript `find . -name something.txt` The problem is that some of the pathnames ...
5
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1answer
197 views

Shell one-liner for adding a line in the middle of a pipe

I write a script which sends the input file to CPP, then to grep, then to a certain program: cpp $1 | grep -v "#" | theprogram But, "theprogram" requires the input to start with a certain constant ...
4
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2answers
191 views

Why sed prints first string from file even if it's failed to find matching groups

I'm trying to write sed expression which will extract matching groups from file. E.g. I have .cue sheet and I want to extract it's genre tag. It has following format: $ cat file.cue | grep GENRE REM ...
2
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2answers
292 views

Nature of the positional parameters

I am beginner to shell scripting and wrote this script which sort of confused me a bit... function func { the variables received are echo $0: $1 and $2 } echo in the main script func ball boy The ...
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2answers
8k views

sh script will not execute as root (cron)

I have the following script added to cron. If I add touch thisisatest.file to the first line it will create a file named thisisatest.file, but not execute the rest of the code. If I manually type ./...
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1answer
1k views

Alias for redirecting both standard output and standard error, as well as sending to background [duplicate]

I am trying to create an alias for redirecting both standard output and standard error of gedit to /dev/null, whilst sending the command to background. This works: $ alias gedit='gedit $1 > /dev/...
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3answers
8k views

identify files with non-ASCII or non-printable characters in file name

In a directory size 80GB with approx 700,000 files, there are some file names with non-English characters in the file name. Other than trawling through the file list laboriously is there: An easy ...
0
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1answer
585 views

Passing multiple scripts to shell over ssh

I have a somewhat lengthy script which sources other scripts to include the functions there. I'd like to execute this script remotely via ssh. Now I thought to make one script file of it (without ...
4
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3answers
2k views

Help Shell script to pass variables to rsync

I'm trying to create a simple wrapper shell script for rsync. When I send file names to my script, rsync can never seem to identify the correct location. The file names have spaces in them. I've tried ...
2
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2answers
205 views

Process each line from text file and delete related files from disk

I used the find command to find several files and folders and output them to a text file like so: nohup find /oradba -name '*soapr*' 2>/dev/null >find_soapr_db40.txt & So instead of ...
8
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1answer
254 views

Filter the clipboard content without using an intermediate file

I'm trying to modify the text that is in my clipboard, remove certain lines of that contains some strings and then get the output for further manipulation (I prefer coping to my clipboard only if I ...