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

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How can I use arptables to limit the number of outgoing ARP requests a second?

End goal: Make a script that will limit the number of outgoing ARP requests in a second using arptables. This is to have the ability to not trip the ARP-limiting feature on Cisco devices. I want to ...
1
vote
1answer
16 views

What's the Fedora equivalent of /var/lib/dpkg/info/[…].prerm?

Example file: /var/lib/dpkg/info/util-linux.prerm What's the Fedora equivalent of this file? (Not limited to util-linux - generic question for any package.) Use case: A prerm script is failing. ...
0
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1answer
24 views

How to execute R script attaching it to a shell script in Linux?

I am trying to submit a job to be executed on cluster. And this is done by writing an sbatch submission script. The job involves opening R 3.1.3 and running the referenced R script on the server. ...
0
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1answer
44 views

Files of specific extension in directory to be sorted by modified time and then stored in array

I have found many answers to sort the files of directory and even to save them in an array. Sorting Example ls -t Directory listing in array array=(*) My particular problem needs to sort files ...
7
votes
1answer
277 views

Are [ “$VAR” = “” ] and [ -z “$VAR” ] always equivalent?

My code looks something like this: VAR="" while [ -z "$VAR" ]; do VAR=$( command | grep "important_string" ) done So I want to poll the output of command, until the important_string appears and ...
0
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2answers
34 views

Linux Command Syntax not getting what is it

I am not a Linux guy but stuck in some Script which I have to read for my Project. So can anyone can help me what this command is doing? shift $(($optind - 1))?
0
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4answers
88 views

The first Line of Scripting [duplicate]

what does #!/bin/bash at the 1st line mean ? Is it just a comment and ignored by the shell like all other comments in program OR Only this line is interpreted by the interpreter and all the other ...
10
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2answers
370 views

Differentiating between running and being sourced in a bash shell script?

Either what I'm asking here is extremely unorthodox/unconventional/risky, or my Google-fu skills just aren't up to snuff... In a bash shell script, is there any easy of way of telling if it is ...
1
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1answer
44 views

validate the sequence number in the trailer of a file

We have a file that arrives daily and has a sequence number in the trailer like 9999 TR SAP _AP Distribution 0000000000000001 where 0000000000000001 is the sequence number and the file that ...
-3
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0answers
25 views

Find the number of jobs present in each box. Find the number of child box in each parent box [on hold]

BOX_A--------------------SUCCESS JOB_AA--------------------SUCCESS JOB_AB--------------------SUCCESS JOB_AC--------------------FAILURE BOX_B--------------------FAILURE ...
-2
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0answers
16 views

script to check availability of mail server domain using wget command in solaris 10 [on hold]

#!/bin/sh /usr/sfw/bin/wget --secure-protocol=SSLv3 mail.google.com 2>&1 | awk '/^ /' if [ $? -ne 0 ] then echo "Server is UP" else echo "Error: URL "mail.google.com" is not ...
1
vote
1answer
41 views

Display a line in a text file if variable matches a part in the line?

I'm making a stock checker. I have a file with all of the NYSE exchanges and their descriptions. The descriptions start on the first tab enter of the file. The file formatting looks like this: A ...
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0answers
14 views

Shell Script to Generate Automatic ticket/Email [on hold]

I have a requirement to generate an auto ticket/email when it's time for a scheduled task to be done and it should repeat again when it's time for performing the task. Could you please help me with ...
1
vote
1answer
38 views

Find last line of a file for matching string?

I want a loop that runs infinitely over a file but always checks the last line to see if it contains the matching string if it does then echo that line and keep the loop running. What I have right now ...
-1
votes
1answer
28 views

Starting Debian mono application (that has a GUI) AFTER boot is done [duplicate]

I've been trying to figure out how to start an application after Debian (Wheezy) is done booting up and on an LXDE desktop session. It is a mono C# application. The script I have is simply mono ...
2
votes
2answers
65 views

Difference of using () and $() to execute a series of commands

I am currently trying to make a script that creates bytes that will be piped as input to netcat. Here is the idea of the script: (perl -e "print \"$BYTES\x00\"; cat file; perl -e "print \"More ...
0
votes
1answer
23 views

Want to use find with rsync in script

I'm trying to make a script that will run in cron, that will search a path for specific file name. In the path there might be more folders with that same file name. If found and they are newer than 2 ...
-2
votes
2answers
45 views

How to make a password box in linux? [on hold]

I have a script but can't find mistake: #!/bin/bash data=$(tempfile 2>/dev/null) trap "rm -f $data" 0 1 2 5 15 dialog --title "Password" \ --clear \ --passwordbox "Enter your password" 10 30 ...
1
vote
2answers
29 views

How do I generate diffs for a series of files?

I have a series of a few thousand files, all with filenames in order, so let's say file1.x, file2.x, file3.x, etc. All these files are in the same directory. I know how to generate a diff from ...
1
vote
3answers
46 views

Killing the previous instances of a script before running the same unix script

I want to kill the background process of the same shell script that i am going to run again. That means before executing the shell script i want to delete the background process running for the same. ...
3
votes
3answers
91 views

How to kill this process in bash

I am trying to interface my homemade Raspberry Pi-powered arcade machine with a coin acceptor, and for that I: use a shell script (named gameplay) which starts the game emulator (MAME) when a coin ...
1
vote
2answers
24 views

bash command/script to reset default route

I manage several OpenWrt (embedded linux) routers for which I've written bash scripts to run an Openconnect VPN client. The client uses "vpnc-script" to set up routing, which replaces the initial ...
2
votes
1answer
42 views

Stable timing for shell scripts?

The run times of scripts vary quite much. I would like to find similar time -function as Matlab's timeit, described here. For instance, I am evaluating these commands here about counting quickly ...
1
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1answer
20 views

Conditional file and directory installation in Debian Packages

Is it possible to create a binary Debian package with conditional files and directories installation (e.g. installation of an init script in /etc/init.d/ after being confirmed by user)?
0
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1answer
20 views

How to make sure the same string doesn't appear next to itself in an array?

I'm making a Rubik's Cube scramble generator, and the turns can't be side by side or else it's useless. I'm trying to stop it from doing the following: Displaying the same string twice, i.e R2 R2 ...
3
votes
2answers
124 views

To count number of matches in a mega string quickly

I have big text-data without spaces and without other rows in one line. In reality, the streams are 0.2 Gb/s, similar situation here, but in this task, counting occurrences which is more challenging ...
1
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0answers
34 views

This code isn't working. (Trying to declare array values in a for loop and do math functions on them)

I was again bored and looked up a list of programs to make in bash, and I'm trying to make a CC (credit card) validator. I had to split the characters into an array to do the validation, and I think I ...
1
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0answers
21 views

Exceeding paste's length limits in resulting line? [closed]

I'm in a situation where I am extracting files using Informatica.My problem is that in extreme cases I'm exceeding the maximum length for a resulting line for the header line. I'm on Oracle. What I ...
5
votes
1answer
58 views

Script started as `source` or `executable`?

Can we determine inside the very script whether it started as source (.) or executable (shebang or something alike)?
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1answer
54 views

Pass string value to date in Unix

mm="27 Jun 2011" dd=$(date -d'27 Jun 2011' +%Y%m%d) echo $dd I want to use value of mm in second line. When i tried like below dd=$(date -d'$mm' +%Y%m%d) It is giving error.
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votes
2answers
43 views

shell script not running using crontab

This is my script mboxutil -l > n.txt sed 's/^.*user//' n.txt > n1.txt cat n1.txt | sed 's/^.//' > n2.txt sed 's/\/.*//' n2.txt > dss_list.txt rm -f n.txt rm -f n1.txt rm -f n2.txt sed ...
0
votes
1answer
48 views

How to extract particular fields from lines using shell commands?

File1: 27/07/2014 10.10.03 Breaker1 was closed by Mr. A.Basu Spectrum ui6dms 29/07/2014 04.50.53 Breaker1 was opened by Mr. D.Gupta Spectrum ui6dms and one note added 30/08/2014 03.20.01 EarthSwitch ...
0
votes
2answers
66 views

What is wrong with the code? [closed]

#!/bin/bash for ((i=1 ;i<=3;i++)) do echo "Enter gallon used(gal):" read gal echo "Enter Miles Obtained(mil):" read mil mileage=`echo $mil / $gal |bc` echo "scale=4; $mileage " | bc c=`echo $c + ...
0
votes
3answers
52 views

Bash: increment a variable in a while loop?

Bash newbie here! I have a bash script that for each file in a set, greps each line in the file for a string. Then it splits the line on commas, converts the 7th element to a float, and increments a ...
6
votes
3answers
274 views

Should I use a slash at the end of path variables in shell script or not? [closed]

Today when writing my shell script. A question suddenly comes to my mind. Since cd /target_dir and cd /target_dir/ both works. Should I add a slash at the end of my path variables in a shell script? ...
-3
votes
1answer
43 views

sed/awk - replace first occurance of a string with array of strings [closed]

I want to find the first occurrence of a word and replace it by 3 strings using sed/awk. for example , I have the below entry in my /etc/hosts file 10.4.16.11 dispatch1 10.4.16.12 dispatch2 ...
2
votes
3answers
205 views

Am I using a while loop wrong?

I found a list of projects to do, and one of them was something that generates amounts of change. I made this code: getamt() { echo "Enter amount of money." read amount echo "OK." } change() { ...
0
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2answers
45 views

validate record count in header

I am trying to write a script that should verify total detail records equal to the Record_count in header record, If not throw an error sample data 0001 HD SAP _AP Distribution 20150615 131723 ...
0
votes
1answer
18 views

Substituting the value with spaces for a variable in bash script - the correct way

I have a compilation script that can compile the program with and without the debug symbols. I want to ask via bash prompt ( read ) the user to choose whether he wants a debug version or not with ...
0
votes
1answer
29 views

Export mysql to remote server using one SSH session

I've come across a situation where I had to create a utilitary shell script that would be executed in many servers from different regions. The objective is to dump the local mysql database, copy it to ...
-2
votes
1answer
39 views

Comma and newline replaced with comma [duplicate]

How can I find the solution to replace ":" and newline with comma, and to remove "./" below is the sample format. ls -lRm ./www.toncemoy.com: www_ttoncemly_com, www_ttoncely_com, www_toncethly_com, ...
0
votes
0answers
52 views

comma and newline to be replaced with comma [closed]

Can anyone help me finding the solution to replace comma and newline with comma, below is the sample format. www_sngforadultadhd_com, www_scegforadultadhd_com, www_scegforadultadhd_com, ...
4
votes
4answers
106 views

How to Check the existence of multiple files in a directory and zip the same

I am facing an issue while checking the existence of files ending with the same string/pattern. The file names might be as follows abs_123.unl xyz_123.unl Currently my code is as below and working ...
1
vote
1answer
46 views

Syntax error at a semicolon in a shell script

The one liner command will be longer but this is the part that is throwing the error. for user in natural1 ; do cat <<EOT >> /home/$user/public_html/.htaccess <FilesMatch ...
1
vote
1answer
29 views

Silent installation of shell script using bash file [closed]

I have a setup file for Linux which is in shell script format. I'm trying to perform a silent installation by writing a bash script. When I directly access the script I'm unable to suppress the setup ...
3
votes
1answer
173 views

Approximating a floating point number with correct rounding off

How can I approximate a floating point number using shell-script (say, up to 4 digits after the decimal point)? I have two examples: A=1.2345678 and B=1.2345678E-05. So I would like to get ...
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votes
0answers
55 views

Bash Shell - Grep a line from a file - append from an entered variable and query that line?

I would like to grep a line from a txt file use that line and append the variable used "entered from the user. Get the output of the grep add variable with a space and then query that line. Any ...
1
vote
6answers
172 views

Hiding Password in Shell Scripts

How can I hide a password in shell scripts? There are a number of scripts that are accessing database. If we open the script others also aware the username and password. So if anyone knows how to hide ...
0
votes
3answers
57 views

Creating a script that runs a simple command for all files in a directory

I need to use the text-based browser Lynx to dump 1000s of html files into text files, with the same filename. For any given filename.html the command is lynx filename.html --force-html --dump > ...
0
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1answer
44 views

Practical usage of “shift” shell builtin command?

I checked the /usr/bin/ssh-copy-id(part of openssh-client package at least under Debian) shell-script and it contains following if-statement: if [ "-i" = "$1" ]; then shift # check if we have 2 ...