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

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1
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1answer
71 views

Divide a variable by a number? [duplicate]

Basically I need to convert centimetres to inches which I am trying to do by diving the area in centimetres by 2.54. But I just cannot get this to work. echo "please enter width and then height" ...
4
votes
2answers
105 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 ...
0
votes
1answer
27 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
47 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 ...
3
votes
2answers
158 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
62 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
70 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. ...
0
votes
1answer
74 views

Run smartctl on all disks of a server [Solved]

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 ...
3
votes
1answer
52 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 ...
3
votes
2answers
69 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
54 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 ...
10
votes
7answers
260 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 ...
-1
votes
2answers
23 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
109 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 -> ...
4
votes
3answers
86 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
63 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 ...
2
votes
5answers
294 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
30 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 ...
3
votes
2answers
40 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
44 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
50 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 ...
11
votes
4answers
1k 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
88 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. ...
4
votes
3answers
193 views

Check if 2 directories are mounted 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.
2
votes
4answers
104 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
68 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
70 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 ...
1
vote
3answers
98 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 ...
0
votes
0answers
48 views

bash script to check zabbix java gateway

I wrote simple script to check status of a service and when service is down search live processes for the service and kill them, then remove pid file and restart service. The problem is that the ...
21
votes
7answers
813 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 ...
3
votes
6answers
118 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
47 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?
1
vote
3answers
43 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
666 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
36 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
70 views

how to get particular port number using shell script? [closed]

RABBIT_PORT=$(netstat -tupln | grep beam) echo $RABBIT_PORT Output : tcp 0 0 0.0.0.0:47858 0.0.0.0:* LISTEN 4533/beam tcp6 0 0 :::5672 :::* LISTEN 4533/beam I want to extract the ...
3
votes
5answers
171 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 ...
-4
votes
3answers
134 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
86 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. ...
2
votes
4answers
117 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 ...
0
votes
2answers
79 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 ...
7
votes
7answers
907 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
54 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 ...
0
votes
0answers
31 views

How to install libevent tmux?

I've been trying to install libevent / ncurses / tmux into '$HOME/local', but am having an issue running .configure for tmux. What I am trying to do is install it as follows: TMUX_VERSION=1.8 ...
6
votes
4answers
289 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
49 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.
1
vote
1answer
29 views

Creating shell script on Desktop and not getting a prompt?

I have created a shell script on Desktop. Whenever I open it , I get a prompt to either run in terminal, display and etc. How to remove this prompt?
2
votes
1answer
65 views

Find out if files in a folder exist under other name in other folder

Possibly a little incorrect English ahead: There are at least 2 folders. For this, A contains files without extension, usually usernames, and B contains similar files, with '.yml' extension or ...
1
vote
2answers
77 views

What's the difference between print and head?

I know head gives you the beginning section of a file. But in this case, I'm trying to go through my source control and find every file that has a shebang line. And I'm failing to get results when I ...
1
vote
0answers
80 views

shell script to check if process is running [closed]

I want to implement a shell script in Ubuntu that checks if process is running. If not, I want it to launch existing byobu (screen) session 1, and then run the command "mygateway" which will run the ...