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

learn more… | top users | synonyms (2)

0
votes
1answer
28 views

Correct syntax for inputting date variable into date calculation code

In my script, the following code successfully produces a timestamp variable for $n in the format 2016-04-28T15:47:48 for n in $(perl parsetime.pl | sed "s/.....$//") do echo $n result is: ...
1
vote
1answer
66 views

Escape strings to be posted via curl

I am trying to make a script that takes some atom feeds and posts them to slack through the Slack API via curl. What I have now works for simple texts, but some of them have double quotes or & ...
1
vote
3answers
57 views

how can we use multiple variables in single for loop in shell script?

I am implementing as below code using for loop but wrong output coming after running the script. for i in `awk -F"|" '{print $1}' $INPUTFILE`, j in `awk -F"|" '{print $2}' $INPUTFILE` do echo $i:$j ...
1
vote
2answers
37 views

loop create from file

I have a file(test) It contains two columns and two lines pippo mm pluto tt I would like to create directory,owner and create password I do some think like that while IFS= read a b; do mkdir ...
2
votes
1answer
39 views

How do I check for the existence of a process without a failed exit code being returned?

I’m using Amazon Linux. I want to start a process provided one isn’t running already. This is a bash script I embed within a Jenkins Maven job. So I have pids=$(pidof /usr/bin/Xvfb) if [ ! -n ...
0
votes
1answer
36 views

unzip without replacing original file and report to log

I want to write a bash script to decompress a file without overwriting the original one and redirect the operation result into a log file. I found an answer to the first part of my question at: How ...
1
vote
1answer
37 views

cannot get screen command to execute code containing DISPLAY=:0

I am trying to ssh into a remote machine and run a shell script, which opens a GUI. I want the GUI to open on the remote machine and remain open (so I am using DISPLAY=:0 nohup). I tried: ssh -t ...
0
votes
1answer
22 views

Dynamically write bash script from another?

I am trying to dynamically create and write to a file a bash script from from a current bash script. echo "## Get the IP of the system that was assigned #!/bin/bash ip=$( hostname -i | xargs ) echo ...
0
votes
1answer
21 views

Including milliseconds in a Script?

sudo hexdump -v -e '1/1 "%02x\n"' /dev/ttyUSB0 | awk '$1=="ed" { getline byte1 getline byte2 number = strtonum("0x" substr(byte2,2,1))+2 ...
0
votes
1answer
16 views

Setting XDG_CACHE_HOME Breaks Firefox Installation

In my .bashrc I set my XDG_CACHE_HOME variable to "~/.cache/". This breaks my Firefox installation, telling me that it cannot load my profile. Without this line, Firefox loads properly. I have ...
0
votes
1answer
21 views

printf in my output now

The encryption on this problem just got more interesting. I started with this script: while read CTFlist; do #next we need to create ctfs padded with zeros as a variable ctfPadded=(printf ...
-1
votes
1answer
57 views

add multiple .csv files using bash command

I want to iterate over all randomly generated CSV files in a folder using using bash and add them line by line. Each CSV files has 3 rows, the 1st row indicates just the number of generated files and ...
-1
votes
2answers
43 views

Use of && and || operators to handle the result of the same command

In bash, is it possible to use these two operators to handle both of the exit statuses of the same command ? or if I want to handle both cases, I have to use an if statement ?
0
votes
3answers
49 views

sed substitution

I have a string as follows: /test/test/ 12 /test/test My goal is to turn it into: /test/est/ 12 /test/test This is the command: echo "$x" | sed 's@\(/*/\).@\1@g'" I am using at the moment but ...
2
votes
2answers
317 views

How can I redirect the output of a child process?

I am running the following git clone command through sudo and bash and I want to redirect STDOUT to a log file: % sudo -u test_user bash -c "git clone https://github.com/scrooloose/nerdtree.git ...
0
votes
1answer
34 views

getting links including outer html

From a html page with lots of links, I'm looking for a way to extract only the links that follow a specific format. <a href="https://always/same/link/same-name_19.html">always same ...
0
votes
2answers
47 views

Binding Timestamp with Hexdump?

I am running a script which is given below, sudo hexdump -v -e '1/1 "%02x\n"' /dev/ttyUSB0 | Many Pipes | gawk '{ print strftime(":: %s"), $0 }' Here the data is being hex dumped with timestamp ...
0
votes
3answers
44 views

BASH: pass arguments to sub-script

I have a script like this: #!/bin/bash . config ./sub-script There are a lot of variables in config and I don't want to pass them to sub-scirpt like ./subscript arg1 arg2 ... arg100500. Also, I ...
0
votes
0answers
32 views

How can I create a script to do not mount pendrives for some time?

I'm new to Linux (I'm using Ubuntu 14.04) and I want to create a script to deny pendrive mounting. What I want: root user deny pendrive mounting to everybody except him for 4 hours. More: how to ...
0
votes
5answers
73 views

Adding time stamp to a log file?

I am running a script file. I have written a while loop inside the script in which I have pipelined multiple commands like awk, sed and finally I am writing the output to a file using > operator. I ...
0
votes
1answer
33 views

Bash script using mysql command with variables failing

I have a script to clone a vhost and associated db - however one of the mysql commands doesn't work. It fails and ends up outputting the mysql version number and 'how to use' info as if it hasn't been ...
-2
votes
2answers
65 views

standard deviation using awk [closed]

I am using below command to get standard deviation of file A names 1 2 3 avg 23.3107 20.0372 21.7236 21.6905 awk '{x[NR]=$0 ;} END{a=$4; for (i in x){ss += ...
1
vote
1answer
47 views

Creating a complex variable content by hand

I am creating a shell script dynamically and sending it to a remote server for execution. All is working except when I try to inject a variable with content coming from a file with multiple lines, ...
0
votes
6answers
100 views

how to do formatting of a file in unix

I have a file file.txt. which have below three records. <ResultDescxmlns="http://www.mpaet.com/boe/interface/common">Operation successful. 220095 9251000014 Now my desired format should be as ...
0
votes
1answer
38 views

How to replace a text in a shell executable file (.sh) using Python?

I have xxx.sh file which content is: setsid ./start-meteor.sh >> /home/farah/StudioInstallation/Studio/bricks/platform/log/databricksastro.log 2>&1 < /dev/null & I want to ...
1
vote
1answer
50 views

BASH Variable checker function

I am struggling to figure out a way to reduce code duplication. Specifically when checking if a variable is set. My code currently looks like this: # webadmin enabled if [ -f "${servercfgfullpath}" ...
0
votes
2answers
99 views

Why does `read` not pick up all my vars?

My apologies for the very basic question, but can someone please help explain why the following does not print 3 2 1 6 5 4? echo '1 2 3 4 5 6' | while read a b c; do echo result: $c b a; done ...
0
votes
0answers
56 views

Executing remote code with arguments

Why this: ssh -i ~/.ssh/master.pem ec2-user@xx.xx.xx.xx 'bash -s' < `dirname $0`/elements/"$element" returns hostname.sh test-5000: No such file or directory when $element is not a just a single ...
-1
votes
2answers
86 views

Script that will show area of rectangle

I am looking to write a script which will prompt the user for two numbers, representing the width and height of a rectangle in centimetres, and output the area of the rectangle in both square metres ...
-1
votes
1answer
40 views

Arithmetic expressions in for-loop

In for (( expr1 ; expr2 ; expr3 )) ; do commands ; done expr1, expr2, and expr3 are arithmetic expressions. Is expr1 ; expr2 ; expr3 not an arithmetic expression? (( expr1 ; expr2 ; expr3 )) ...
3
votes
3answers
38 views

How to pass array to bash shell script?

How do I pass an array as a variable from a first bash shell script to a second script. first.sh #!/bin/bash AR=('foo' 'bar' 'baz' 'bat') sh second.sh "$AR" # foo sh second.sh "${AR[@]}" # foo ...
2
votes
1answer
28 views

Bash shell script program that prompts for and reads two integers from the user.

Okay, so I been trying to figure this problem for a while and I'm coming up with errors left and right. This is my first time trying to learn the basics. So any advice would be helpful! Problem: I'm ...
2
votes
2answers
66 views

Accessing array index variable from bash shell script loop?

I want to access the array index variable while looping thru an array in my bash shell script. myscript.sh #!/bin/bash AR=('foo' 'bar' 'baz' 'bat') for i in ${AR[*]}; do echo $i done The result ...
0
votes
1answer
28 views

Automating Backup and Shutdown

I want to backup my entire internal hard drive files into an external hardrive and execute system shutdown once the backup is finished. The reason why I want to do that is to execute the backup during ...
1
vote
1answer
33 views

Join two files in a batch mode

I have many files with the following names: 0001mm.xyz , 0002mm.xyz , 0003mm.xyz ... 0001qm.xyz , 0002qm.xyz , 0003qm.xyz ... I want to join the contents of 0001mm.xyz and 0001qm.xyz ...
3
votes
2answers
79 views

Changing a file's modified date based on date in file name

I have a directory full of photos with file names in this format: IMG-20160305-WA0001.jpg. The date taken is obviously in the file title. Unfortunately the date modified on all files is today. I ...
3
votes
3answers
221 views

Why and when should eval use be avoided in shell scripts? [duplicate]

Many answers and comments on this site mention that one should generally avoid using eval in shell scripts. Often these comments are addressed to beginners. I've seen mention of security issues and ...
1
vote
1answer
42 views

Aligning Hexdump Data in a Specific format?

I am reading serial data from my Raspberry Pi and all I am doing is a Hexdump I have to find the header and then go to the 2nd byte of data from header for ex: ed 13 74, I have to take the value 4 , ...
0
votes
4answers
48 views

Setting variables from shell: how to use them in a script?

How can I set variables to be used in scripts as well? They don't have to be global / system-wide, just the current session is sufficient. But for some reason they seem gone even if I run a script ...
1
vote
2answers
41 views

Detect and remove empty directories from list

A common problem game developers have with the Unity3D engine and Git is that Unity and Git fight for whether an empty directory should exist or not - Git doesn't care, Unity3D will keep making git ...
0
votes
1answer
43 views

Need help parsing a filename and adding it to a text file

I have a directory full of files with the date they were created in the filename (ie "mvr-20160420.csv"). The files contain comma delimited data that I'm combining into a single text file. I'm ...
0
votes
2answers
35 views

Shell script for executing programs within a loop and checking their exit values

How do I do this in a shell script: for (int i=0;i<1000;i++) { run applicationA run applicationB if (retvalFromApplicationB!=0) {continue;} else {pipe ouptut (stdout) from ...
-1
votes
2answers
45 views

shell script replace and add next line with special characters [closed]

I am trying replace a line with another line and add new line below that using a shell script. I want to replace: export PATH with: ...
0
votes
1answer
57 views

associative array with two strings

is it possible to loop a simple array with key and value with a string in the [key] part ? #!/bin/bash -x wget url://stringlist1 wget url://stringlist2 #cat/sed some stuff .... declare -A ...
1
vote
1answer
40 views

Rewrite a find command that uses sed -i for AIX

I have a script that searches for a string and replaces it via the sed command. If that string contains special characters, the script will escape them (except for the slash because it's my current ...
2
votes
2answers
50 views

pssh (Parallel-ssh) passing different parameter for every host

I have a file called hosts which looks as follow: host1 host2 host3 host4 ..... On these machines there is also a local user named as the machine name. host1 user is created on host1 host and so ...
1
vote
1answer
38 views

How to add an word for a line where transpose has done

I have a file fruits: apple grapes banana orange By using cat < fruits | tr "\n" "," It will give output as apple,grapes,banana,orange, Here I want to print the file name also along with ...
-5
votes
1answer
52 views

help with a bash shell script that creates directories

I have a problem I been trying to tackle. If anyone can help, it would save me a headache! For reference,I started self learning so I'll be looking for problems around but can't find the answer for ...
2
votes
2answers
68 views

bash read of a newline, printf reports character 0

I use bash printf function to print ASCII codes of characters in an input file, but for some reason printf outputs ascii code 0 for LF characters, instead of 10. Any ideas why? while IFS= read -r -n1 ...
0
votes
1answer
53 views

Reading user input with read back

when I use simple bash command #!/bin/bash echo Please, enter your name read NAME echo "Hi $NAME!" and run it using source filename.sh it gives me an error :Undefined variable what could be the ...