Questions about shell scripts, executable files that are interpreted by a shell (bash, zsh, etc.).

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4
votes
2answers
221 views

Spliting `File` and `directory name with space' via shell script

I've got a file called Files.txt having following content: TestApp/Resources/Supporting Files/main.m TestApp/Resources/Supporting Files/AppDelegate.h TestApp/Resources/Supporting Files/AppDelegate.m ...
9
votes
4answers
5k views

How to run parallel processes and combine outputs when both finished

I have a bash shell script in which I pipe some data through about 5 or 6 different programs then the final results into a tab delimited file. I then do the same again for a separate similar dataset ...
0
votes
1answer
2k views

Where are RPM postinstall scripts located?

I have found a bug in an RPM that I have been provided. rpm -qp --scripts foo.rpm > /tmp/badscript cat /tmp/badscript postinstall scriptlet (using /bin/sh): ... if [ 'some bug' == true ].... I ...
0
votes
2answers
331 views

bash function output to pipe [closed]

I made a bash function to beautify svn output, this function show logs one line per commit, it is great! I like it, but if I use it with pipe it does not work. You can find it on github svn-beautify ...
4
votes
3answers
6k views

Range of the command cut in unix

I'm trying to make a shell script, I want to cut a string using the 'cut' unix command, as follows: namecmpaux=$(echo $namecmp |cut -c0-19) But when I run the shell tells me the following error: ...
2
votes
2answers
205 views

Shell Scripting: how to use part of the file path as the file name?

I have a group of directories, each containing exactly 1 jpeg image, like so- /psds/folder1/image.jpg /psds/someotherfolder/picture.jpg /psds/yetanotherfolder/thumbnail.jpg What is the appropriate ...
1
vote
1answer
495 views

Date calculation in script for notification alerts

I want to create account expiry alerts therefore I need to write a script which could alert me before 1 month of expiry over email. I'm working on Linux. I can get expiry information as 2015-27-03. ...
1
vote
1answer
2k views

Run smartctl on all disks of a server

My question is a quite simple , I want to run the command smartctl -i -A on all disks that the server have. Think that I've too much server with different number of disks and RAID Controllers, then I ...
2
votes
1answer
276 views

Turning off default video output with xrandr when external monitor is connected

I'm new to bash scripting, and I'm trying to configure my video outputs so that my laptop display gets turned off when I connect an external monitor via VGA. That's the script I came up with, pretty ...
3
votes
1answer
159 views

Find and Replace Recursive

I want to modify every file in a directory recursively. I want to replace: <?php with <?php /** * * Copyright (C) MyCompany, Ltd. - All Rights Reserved * Unauthorized copying of ...
7
votes
2answers
835 views

shell script header for best compatibility [duplicate]

Which one is better: #!/usr/bin/env sh #!/bin/sh empty/no header I used to think the 1st one is the best, anyway i've found on some Linux-based systems (like Android) that pathname is missing, so ...
0
votes
2answers
117 views

why is ! character used in shell scripts [duplicate]

I recently encountered a situation where I tried to use ! as a record separator for my string array in shell script. When I used it in my shell script, the script got expanded automatically. An ...
13
votes
7answers
5k views

Test if multiple variables are set

I'd like to make sure that at a certain point of a script, after sourceing a configuration file, several variables are set and, if they are not, to stop execution, telling the user about the missing ...
0
votes
2answers
163 views

how to get the return value of wpa_supplicant?

My question is really simple I want to get the return value of the command wpa_supplicant, when connected to the internet, to know that I am connected or not with a shell script.
4
votes
2answers
782 views

Convert every pdf in the current directory to png

I want to write a bash script to convert every .pdf file in the current directory into a .png file. For example: $ls . a.pdf b.pdf $./pdf2png.sh Converting pdfs to pngs a.pdf -> a.png b.pdf -> ...
6
votes
3answers
2k views

How to read user input in pipe?

Let's assume I have a file named confirmation.sh with the following content: #!/bin/bash echo -n "Are you sure [Y/n]? " read line case "$line" in n|N) echo "smth" ;; y|Y) echo "smth" ...
1
vote
1answer
200 views

For loop not getting executed correctly over ssh

I have a script in which I am reading from a csv file where it contains SourceIp, DestinationIP,Source Ports, Destination Ports. First I am reading the sourceIp and trying to do ssh over it (I am ...
4
votes
3answers
1k views

purpose of run-parts(8) utility

At least under Debian-based systems, there is a run-parts utility in debianutils package which is used in various scripts. For example in /etc/X11/Xsession. It will run all the executable files found ...
3
votes
6answers
6k views

How to reverse a string made of digit in bash?

What is the best way to turn out digits in number? E.g. $ echo 123 | hook 321 $ echo 12358 | hook 85321
2
votes
1answer
299 views

gnome-open execute shell script

Is there a way to execute shell scripts automatically using gnome-open? If I call gnome-open script.sh in the terminal, the script opens in the default text editor. However the shell-script is ...
4
votes
2answers
223 views

Bash script : help file inside the script or in a different file?

I'm writing a script that has the vocation to be a fully featured program at the end. As far as I know, BASH is enough for his purpose (manage PPA's, kinda like Y-PPA). I would like to know how to ...
1
vote
2answers
104 views

Bash script is not working

I wanted to create a script that executes the ls command with the provided arguments. Why isn't it working? I tried running it with for example -R, then it echoes (I echoed the same thing for ...
2
votes
2answers
133 views

I want a script which will take multiple column numbers from a user and reverse the contents

I want a Unix script which will take multiple column numbers from the user and reverse the contents. declare -a param="$@" # enter 0 when exit the insert element echo "Enter the numbers" read n while ...
17
votes
4answers
2k views

How Does Linux deal with shell scripts?

For this question, let's consider a bash shell script, though this question must be applicable to all types of shell script. When someone executes a shell script, does Linux load all the script at ...
2
votes
1answer
1k views

Bash Script getting stuck during execution

I have a bash script that is reading a CSV file , that contains source IP address , destination IP address and destination port. My script is basically doing 2 tests: 1 Performance 2 Connectivity. ...
7
votes
4answers
790 views

Check if 2 directories are hosted on the same partition on Linux

How can I check if /my/dir is on the same partition as /? This is for integration within a script. Bind mounts should be handled correctly. POSIX compatible solutions are welcome.
3
votes
1answer
254 views

Need help decoding bash script

Have following line in bash script, parsing input arguments: ((10#$2 > 0)) 2>/dev/null && shift 2 || shift Basically it helps handling parameters with optional integer subparameter. ...
2
votes
4answers
2k views

Parsing process command-line arguments from pargs in a shell script

I get list of PIDs in my bash scripts (Java processes) and have to analyze their command-line arguments to determine which instance of server each PID corresponds to. At the moment I do it that way ...
0
votes
3answers
1k views

I want to create a zipped output file while keeping the original one

I am new to unix command and I have got one scenario that, I want to create a zipped output file while keeping the original one. I want to do it from Informatica end by using command task or session ...
1
vote
2answers
403 views

Supply input to a program with a password prompt

Is there any Linux command which supplies multiple enter keys to another process which is running in a terminal till the other process dies? For example consider the command yes ' ' | ./ssr-sim ...
2
votes
3answers
6k views

How to delete a line with variable search using sed command

I am new to sed. What is wrong with the sed command on deleting the line which matches the input data? InputData.txt 123, 1234, 1453, Datatodelete.txt 1234,hellofirstline 123,hellosecondline ...
24
votes
7answers
1k views

Should scripts that require sudo fail if they don't have it, or use sudo and prompt?

I have a script which gives me fine-grained control over my backlight brightness and requires sudo to run. It's essentially this: backlight="/sys/class/backlight/acpi_video0/brightness" echo $1 | tee ...
6
votes
6answers
2k views

Will $0 always include the path to the script?

I want to grep the current script so I can print out help and version information from the comments section at the top. I was thinking of something like this: grep '^#h ' -- "$0" | sed -e 's/#h //' ...
0
votes
2answers
99 views

How to search '(+1)' character substring in a string

I want to search for (+1) in a string (which is a GDG dataset name to confirm if it is a GDG) and want to get a binary answer if it has (+1) as part of the string or not. Can some one please help?
6
votes
2answers
14k views

redirecting to /dev/null

I'm reading an example bash shell script: #!/bin/bash # This script makes a backup of my home directory. cd /home # This creates the archive tar cf /var/tmp/home_franky.tar franky > /dev/null ...
1
vote
3answers
361 views

Executing bash shell scripts

I am reading an article on executing bash shell scripts. Method 1: Create a directory for your shell scripts and add the directory to the contents of the PATH variable, so that you can execute the ...
3
votes
1answer
721 views

What's the difference between “==” and “=~”?

Given a string and a hash returned by openssl, why using == doesn't match them correctly but =~ does? Background question: How can I force a script to use more resources?
2
votes
2answers
152 views

Script to Recognize HDDs and run Smartctl

I'm thinking to do a script to recognize which HDDs are in use (sda, sdb, etc) and run a Smartctl on each one that's are in use, but I don't know how can I start, anyone can help me?
-2
votes
2answers
670 views

How to get the port number a program is listening on in a shell script? [closed]

I have a program (beam) running, and I need to figure out which TCP / IPv6 port it is listening on. I know netstat will tell me, but I haven't fully been able to parse its output: ...
3
votes
5answers
375 views

How can I force a script to use more resources?

I'm running a very time-consuming script which takes many hours to end. Watching top I see that it's only taking 5% of the CPU at best, usually around 3%. Is there any way to force the script to use ...
-1
votes
3answers
49k views

How to get IP Address using shell script? [duplicate]

Want to get the IP address using Shell script. Without knowing the eth0 or eth1 or eth2 How to get the particular IP address. I am not interest to get localhost address, want to get private IP ...
-4
votes
4answers
477 views

How to add a 3 lines in a file using shell script? [closed]

I have a file, that file contain 10 lines. And now I want to add 3 lines to end of the file using shell script. After add lines, If I run the script again I don't want to add same lines again. ...
3
votes
4answers
2k views

Bash script to output path to USB flash memory stick

How would I return (output) the path to any USB flash memory stick(s) connected to the local computer using bash (Ubuntu and Linux Mint)? Background: I'm providing users with an automated backup ...
4
votes
5answers
8k views

Command to display Memory usage, Disk Usage and CPU Load

I want to display Memory usage, Disk Usage and CPU Load in the following format: Memory Usage: 33/512MB (6%) Disk usage: 4.2/20GB (23%) CPU Load: 0.01 How do I do that?
3
votes
4answers
250 views

How do I make sure that a script is run exclusively? [duplicate]

So I have a bash scripts that does some things (pull from github, delete folders .. etc ..) pretty basic stuff. I usually run it whenever I need a new version of the web app on the server. The thing ...
1
vote
2answers
797 views

How to write an alias function to make dd show progress bar?

According to this article, by replacing: $ dd if=/dev/sda of=/dev/sdb [additional options] with: $ pv -tpreb /dev/sda | dd of=/dev/sdb [additional options] one can augment the default dd ...
8
votes
7answers
4k views

cron Vs. sleep - which is the better one in terms of efficient cpu/memory utilization?

The Case: I need to run some commands/script at certain intervals of time and for this I have two options - 1. set up a cron-job or, 2. implement a loop with sleep in the script itself. Question: ...
1
vote
0answers
78 views

Better approach to generating and adding contents to files

I have an input file like below. 1 First one 2 First two 3 First three 3 Second three I am generating 2 output files like below. #FILE1 1 First one 2 First two 3 First three #FILE2 1 ...
7
votes
4answers
12k views

Check if $REPLY is in a range of numbers

I'm writing a shell script for Linux, using Bash, to translate any video-file into a MP4. For that, I'm using avconv with libvorbis for audio. Inside my script, I have a question for the user : ...
2
votes
2answers
55 views

How to list all the files which were not created on Thursday

I need to delete old backups but I only want to keep Thursday Backups and delete the rest of the backups. Give me some kungfu tips. I'm on RHEL if that makes a difference.