A script is a sequence of commands or instructions that are executed by an interpreter program rather than compiled into a standalone executable program.

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5
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4answers
6k views

Can IFS (Internal Field Separator) function as a single seperator for multiple consecutive delim chars?

Parsing an array using IFS with non-whites space values creates empty elements. Even using tr -s to shrink multiple delims to a single delim isn't enough. An example may explain the issue more ...
4
votes
2answers
146 views

When is 'if' not necessary?

In some scripts, I've seen if conditional statements written as: if [ some_conditional_statement ]; then # do stuff fi or [ some_conditional_statement ] && #do stuff Is the second ...
4
votes
3answers
234 views

shell script problem with using the operators

I am comparing two strings using the levenshtein distance algorithm. I got the PHP implementation of the algorithm from here. I am calling this php implementation from my shell script as below. ...
4
votes
2answers
327 views

Exiting a pipeline if a former command fails

I'm trying to check the number of running and queued PBS jobs by parsing the output of qstat -tn1 from a bash script. So far, this has worked: count () { qstat -tn1 | awk ' BEGIN { R = 0; ...
3
votes
2answers
245 views

Finding missing value in text file

I have a text file with following data. Name Feature Marry Lecturer Marry Student Marry Leader Bob Lecturer Bob Student ...
3
votes
5answers
2k views

Replacing text from a list of replacements. Added complication: backslashes

I have a file A that contains pairs of strings, one per line: \old1 \new1 \old2 \new2 ..... I would like to iterate over file A, and for each line perform the replacement (e.g. "\old1 -> \new1") ...
2
votes
1answer
35 views

Copy files that partially matches another files in another location

I have a list of jpeg files in a directory like this (below is just a sample, like the structure is the same but this there are many fo0# sub-folders, not only fo01 and fo01, where each of these ...
2
votes
1answer
77 views

use mutt to send email through specific port on CentOS 7

What specific syntax do I use to get mutt to send an email through port 587 on a CentOS 7 server? For example, the sender is me@mydomain.com, the recipient is someone.else@someotherdomain.com, the ...
2
votes
2answers
73 views

What do i have to consider to write a script that reacts on a keypress?

I know i can read within a script something into a variable, like this: variable = read But i have to press enter in order to submit the value into the variable. What do i have to know in order to ...
2
votes
3answers
124 views

How can I print only variables defined inside my shell script?

Lets supose some bash shell script like: #!/bin/bash a=3 b=7 set -o posix set In this case, the execution of the set variable or some other of the commands to print environment variables ...
2
votes
3answers
3k views

Comparing text files using Bash and AWK

I have two text files, and I want to compare their corresponding values according to their rows and columns. By comparing, I mean to check if the values are equal and echo if the values are the same ...
2
votes
4answers
2k views

How to use wc and piping to find how many files and directories are in a certain directory?

How can I use word counter and piping to count how many files or directories are in /usr/bin directory?
2
votes
1answer
1k views

Script Command without Junk Character

I'm Using Unix script command to record everything which is output to the terminal and place it in a log file. but when I see recorded file, it also include Junk Character. So how to record terminal ...
2
votes
5answers
1k views

Why is the first line comment of .sh file necessary? [duplicate]

I was told that the first line shebang (#!/bin/bash) is necessary in the shell script file, and the file won't run accurately without this line. But I tested some scripts. They work just fine without ...
2
votes
2answers
3k views

/usr/bin/env: zsh -: No such file or directory

I get the error /usr/bin/env: zsh -: No such file or directory ...when I run an executable zsh script that starts with the following shebang line: #!/usr/bin/env zsh - Also, FWIW, replacing - ...
2
votes
2answers
96 views

Scripting to domain allocation to server

I have two text files: file #1: domain.txt cocacola.com airtel.com pepsi.com file #2: servers.txt 192.0.53.42 , 4 # 4 domains already allocated on server 192.0.53.42 192.53.1.2 , 1 # 1 ...
2
votes
1answer
499 views

Script for courier maildir folders on CentOS LAMP environment

I'm looking for resources to help me build a script to do monthly maintenance of maildir folders for a typical CentOS LAMP VPS hosting environment. I would like to run a script that runs from a ...
1
vote
1answer
40 views

Displaying “No Results” When AWK Command has no output

I have the following code, thank-you to the people who helped me here awk -F: '{if(system( "[ -d " $6 " ]") == 1) {print "The directory " $6 " does not exist for user " $1 }}' /etc/passwd However, ...
1
vote
2answers
69 views

Is it better to use a shebang line to execute a script?

I was looking up shebang and wondering why I would use it. I could execute a bash script using: bash foo.sh or ./foo.sh (with a shebang line in foo.sh) What are the pros and cons of each and ...
1
vote
3answers
48 views

How to access the contents of a file that is used as an argument when running a bash script?

I am running a bash script with its parameters/arguments as files. From inside the script, how do I get the contents of those files? I run the script with this command line: sh script_name ...
1
vote
2answers
82 views

identify harddrive before mounting

I've recently made 2 script that take care of mounting and dismounting a harddrive in linux. The thing that I could not figure out is the following. I am currently mounting /dev/sdc1 to ...
1
vote
5answers
151 views

Create a list of directories

I have a list of names in a text file (list.txt) I want to create a list of folders for the names included in that file. I wrote the following script, but it doesn't work and I don't know what is ...
1
vote
1answer
836 views

How can you run a script triggered by a joystick input?

I'm using a Raspberry Pi running Raspbian to power my arcade cabinet. I want to shut the Pi down using the sudo poweroff command without using the keyboard. I'm thinking the best way would be to ...
1
vote
5answers
2k views

Checking if a file exists in several directories

I've been working on this far too long and need some help. I need a script that will look at files in a directory and see if it exists in one of several directories. I need something like this: for ...
1
vote
2answers
383 views

tail -f equivalent

I am seeing several seconds delay with the tail command. I found the cause for it has something to do with nfs services. I am using arch linux and yet to find out how to disable all these services I ...
0
votes
2answers
179 views

Why do I get Illegal number: {1..3}

Why am I getting ./6_sum_square_difference.sh: 11: ./6_sum_square_difference.sh: Illegal number: {1..3} for #!/bin/sh summing () { the_total=0 num_in=$1 for one_num in {1..$num_in} do ...
0
votes
1answer
240 views

Debian - Using TFTP in a bash script

I'm actually using RPiTC (Raspberry Pi Thin Client). I had create a script to see if my Hostname has the same name than a file. And now I want to say "If my Hostname don't have the same name than my ...
0
votes
2answers
50 views

Copying two words from a string into two variables

I want to get the variables $color and $number from a string that in general is like this: "something, numColor (number)". The color might be W, U, B, R, G. If there is no color the variable color ...
0
votes
1answer
103 views

Shell string escape for command arguments [duplicate]

I'm trying to create "/tmp/pwet/foo bar" with this: DIR="/tmp/pwet/foo bar" ARGS="-p ${DIR}" mkdir $ARGS For integration reasons, I have to keep the ARGS building in 2 steps: ARG = some_options + ...
0
votes
1answer
124 views

Is it possible triggering a script with a change of amount of files in a directory? [duplicate]

Is it possible to create some kind of directory watcher and trigger a script when the folder is not empty? I have a CentOS machine with jenkins CI on it. i would like to create a job that will move ...
0
votes
2answers
2k views

Change motd value in UNIX Operating System

I need to change the value of MOTD using a script but I do not know how I should start. Am attaching sample MOTD if anyone can help.             ...
0
votes
1answer
266 views

Bash script installing within multiple directories [closed]

I am attempting to write a bash script that will install rbenv from beginning to end. I am on a Mac for interest sake. But there are some things that are not working mainly i am changing the ...
0
votes
1answer
696 views

Script with root permission [duplicate]

Possible Duplicate: Redirecting stdout to a file you don't have write permission on I am creating a script to change the brightness of my laptop. I discovered that I can do this using ...