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

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1answer
37 views

POSIX shell scripting and performance tuning [on hold]

Nowadays, I'm researching for performance tuning for shell scripting , And I have been prevented to POSIX shell scripting, However it's only a standard, But I think it's rathar than standard for do ...
4
votes
1answer
36 views

Settings environment variables from a file

I want to have a file (outside of git) that contains certain environment variables. While a script (which is in git) needs to read them and export to env. My current implementation works for ...
1
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0answers
27 views

BASH: Fifo troubles - seems selective about input

So I am having a problem with a BASH service in Debian 7 that I've been working on for quite a while and that randomly started having trouble with its fifo, or so it seems. It is based on kind of your ...
2
votes
1answer
33 views

How to detect if DE is Unity or XFCE via shell script?

I have a few configuration scripts that I run everytime I install a fresh version of Ubuntu. Recently, however, I migrated to Xubuntu. I would like to use the same script for both distros, since both ...
6
votes
4answers
314 views

How to atomically allocate a loop device?

I am writing some shell scripts to handle some disk image stuff, and I need to use loop devices to access some disk images. However, I am not sure how to properly allocate a loop device without ...
4
votes
6answers
117 views

Append something to each list in a file

I have a file, lists.txt, that looks like this: // stuff at beginning of file var list1 = new Array(); i = 0; list1[i++] = 'a'; list1[i++] = 'b'; ... list1[i++] = 'z'; var list2 = new Array(); i = ...
0
votes
3answers
25 views

Output to variable with an indirect command (eval)

What is wrong with this indirect command when run with eval ? #!/bin/bash OS=AIX host=myhost CMD_AIX="(o=\`host \"$host\" \`)" CMD=\$CMD_$OS echo $CMD eval echo $CMD eval "$CMD" Ouput: $ ...
2
votes
4answers
96 views

Script to log temperature

I have been trying to write a BASH script to log my raspberry pi's temperature. My plan is to run it as a crontab every 15 mins or something. However I keep getting errors, I think it's something to ...
4
votes
3answers
241 views

How to use printf and %s when there are color codes?

I had these lines: if [[ $# -eq 0 ]]; then printf "$fail_color Error - Function: $function, Line: $line_number \n" printf "do_test: Third parameter missing - expected result\n" exit 1 fi This ...
1
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3answers
44 views

Find a file with the extension .csv in a directory matching a pattern

I have a folder in which I have many subfolders. The Root folder name is allCSV and sub foldername is will be like a_date(s), b_date(s), c_date(s) ... I want a file which is in a_date(s) and ends ...
0
votes
1answer
27 views

cant run dd command on android device

The main objective is to send a splited file to an android and join it back up with a .sh script, the file is splited to 5MB parts but its total size is unknown (trying to make an universal script), ...
5
votes
3answers
179 views

Easiest way to find missing quote in a bash a script?

I have a bash script which is currently 700+ lines long. After a particularly long round of editing, it now errors like so: ./run_me.sh: line 693: unexpected EOF while looking for matching `'' ...
4
votes
4answers
134 views

Move files by date into different directory using CLI

I have a large number of pictures from an old hard drive that I'm trying to organize. If I run ls -l, I notice all of these files have a creation date of 2012 or before. Ideally, I'd like to move ...
2
votes
0answers
49 views

Checking if a specific key is pressed in shell script

Is there a way I can check if a specific key is pressed in a shell script which is running in background. Consider I am running a shell script which has to play a play list of songs as soon as I press ...
2
votes
4answers
78 views

Extract two values from the output of a command

I'm using the following command in a script to get synthetic wifi info: echo "$( iw dev wlp1s0 link | grep '^\s*SSID:\s' | sed -r 's/^\s*SSID:\s//' ) $( iw dev wlp1s0 link | grep ...
1
vote
1answer
66 views

Which one works faster - regular operators (such as <,>,=) or using (-lt, -gt, -eq)? and why?

Which one works faster - regular operators (such as <,>,=) or using (-lt, -gt, -eq)? and why?
2
votes
3answers
46 views

How can I prepend and append to each member of an array?

I have an array: CATEGORIES=(one two three four) I can prepend to each array member using parameter expansion: echo ${CATEGORIES[@]/#/foo } I can append to each array member the same way: echo ...
0
votes
1answer
36 views

Test variable in a bash case statement

What I want is simply to do something if the first variable of the script is empty, in a case statement. Unfortunately I spent yet a certain amount of time searching for the solution but didn't find ...
0
votes
2answers
27 views

Timeout function return value

I'm using the timeout function on debian to wait 5 seconds for my script. Works great but the problem I have is that I need a return value. Like 1 for timeout and 0 for no timeout How am I going to ...
3
votes
0answers
39 views

Bash Script — ffmpeg not being invoked as expected

I'm working on a bash script to convert my music library to ogg* but executing the right command is somehow eluding me. This is the line that should accomplish it: ffmpeg -i "${file}" -f flac pipe:1 ...
0
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0answers
16 views

Why “killproc” command is unable to terminate a script(whiled loop with inter sleep)? [on hold]

How to terminate a whiled loop script using "killproc" without using script's pid?
0
votes
1answer
23 views

PHP script to monitor process and write status to a file

I want to write a php script for monitoring particular process using top command and write into the file. I use top -p pid for monitoring a particular process and also i write a shell script for ...
3
votes
4answers
41 views

How to get the PID of a sub process across to the parent process in a bash shell script?

My shell script is as following: #!/bin/bash ./process1 #It will create a sub process: sub_process1 while [ condition ]; do break done kill -9 process1 and sub_process1 In my script, it will ...
16
votes
5answers
877 views

How can I propagate my SSH pub key to a list of servers without having to type my password in over and over?

I was recently given username/password access to a list of servers and want to propagate my SSH public key to these servers, so that I can login more easily. So that it's clear: There is not any ...
1
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1answer
16 views

Script samba password but securely

I want to script the addition on a samba user and the password. I have seen solutions similar to the one here Piping password to smbpasswd echo -ne "$PASS\n$PASS\n" | smbpasswd -a -s $LOGIN but ...
1
vote
2answers
32 views

Url Decoding shell script

How can I store the url-decoded string in a variable using shell script #!/bin/sh alias urldecode='python -c "import sys, urllib as ul;print ul.unquote_plus(sys.argv[1])"' ...
0
votes
1answer
19 views

Help killing off Process for Mem Leak

I am currently building an Android LP kernel, and have some pretty sweet tweaks already running and built into it. I know there are numerous LP memory leaks (i've already got the bootanimation one ...
-1
votes
1answer
31 views

Webpage content - search for pattern & save to file

I have a web page, say https://test.salesforce.com. I would like to search for a pattern, e.g. "src" at the beginning of a line in the entire webpage content. If the pattern is found, I need to ...
0
votes
0answers
23 views

Run Loop between starttime and endtime and get data from url

I want to check two conduction and run a loop for every one minute. There should be three variable start_time, end_time and current_time Conduction's: start_time should be greater than ...
2
votes
1answer
43 views

How do I properly escape this long su + sed command?

#!/bin/bash wineuser=tom su $wineuser -c "sed -i '$ialias ptgui "wine ~/.wine/drive_c/Program\ Files/PTGui/PTGui.exe\"' /usr/people/$wineuser/config/cshrc.csh" The acutal line inserted to tom's ...
14
votes
3answers
354 views

Prepare answers for questions of a command

Let's say I want to write a shell script that executes just one command. But this command is poorly designed. It doesn't offer any command line options; instead it asks some questions and waits for ...
1
vote
0answers
39 views

Shell Script to change user shell

I am writing a script that would be invoked to change user shell. The basic requirement is that once user gets authenticated (e.g: thorough some web application) the script would be invoked to set the ...
1
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1answer
48 views

Getting an output error with command head in shell script

getting an error with head command. There are two files with size 48bytes in directory and its printing once along with the directory path instead of twice. Why the head command is not considering the ...
1
vote
0answers
26 views

Inherit IO redirections from a script to another

When I redirect the output of a script within a script, I expect the redirection to be applied to the called script as well as the program called within it. A: ./B 2>> error.log B: ...
0
votes
1answer
28 views

Delete excel files which are older then 1 month

I need to delete excel files which are older then 1 month. need to set cronjob. any suggestion for this? which script can be used to search excel files from particular directory and delete them.
0
votes
1answer
37 views

need to get the command information over ssh and the input from file

I am writing a script to get the command information of the remote machine usinf while and for loop. PFB the script. But the script ends by giving the single command information only. I have multiple ...
1
vote
3answers
95 views

How to decode base64 text in xml file in Linux?

I'm new in linux (shell). I need to decode base64 text in xml file using linux shell script. Could you please help me to write linux shell script for decoding the values of those tags where attribute ...
0
votes
1answer
23 views

Percent Signs for Shell Vars to Remove Extension [duplicate]

for file in *.pdf ; do newname=${file%\\.\*} done I don't understand how the %\.* is removing the file extension, can someone walk me through it.
1
vote
1answer
26 views

Issue Using Crontab to Create/Restart Screen and Run Command

I want to have a certain script (rails rake task) running on my server at all times - it basically populates my DB using a live feed. I can create a screen (http://linux.die.net/man/1/screen) and run ...
0
votes
1answer
37 views

Parsing string on multiple parts without separator

115:wc -l:find . -iname "*test*":find /tmp/ -iname "*test*" I would like to parse the string above. In my case, a string consists of 4 columns (every command has : separator) but it can be much ...
2
votes
3answers
68 views

Help with String manipulation in shell

I was writing a shell script to generate a string in a particular format so that it can be used as a input in one of the XML I am working with. Given a input file in the format <attribute ...
4
votes
4answers
212 views

How can I copy a file in a bash script and rename it while copying and place it in the same directory

How would I copy a file "file.doc" and rename it while copying to "file_copy.doc" and place it in the same directory ? And this only by calling the script and adding the file name in the argument: ...
0
votes
3answers
63 views

How to store the output and print it back again with breaking output into new lines

I want to store the output in a variable and want to be displayed as follows. My code: #!/bin/bash dir=$1 printf "file size: %s\n" \ du "$dir" -hab | sort -n -r |tail -n 2 I want ...
3
votes
2answers
73 views

shell scripting remote commands through ssh

I'm trying to create a shell script which will execute some commands which I require frequently. I made the ssh login to skip the password prompt using a public/private key pair. and after some ...
0
votes
0answers
26 views

Script to restart failed jobs [closed]

I want to create a script which may have multiple JOB names which will first check the status of a job whether the JOB is failed or successful. If it fails then start the job again. I am a self ...
0
votes
4answers
63 views

Hexadecimal number sequence checker in Linux?

I have a list of hexadecimal number. I would like to check whether they are in sequence or not. That is, they should be consecutive numbers, in increasing order. In other words, there should be an ...
0
votes
0answers
44 views

Shell script to send alert if mount point exceeds 75% [duplicate]

How to write shell script to send an alert if any file-system on server exceeds 75%, in one email notification instead of receiving separate alert email notification for each file-system. I am ...
1
vote
1answer
51 views

what is meant by “^$1” in shell script?

#!/bin/sh #emp3.sh: using if and else # if grep "^$1" /etc/passwd 2>dev/null then echo "pattern found - job over" else echo "pattern not found" fi in the above programme what is "^$1" and ...
1
vote
3answers
142 views

Find records present in file 1 also in both file 2 and file 3

I have three files file1.txt, file2.txt, file3.txt and they are of same format. I want to select records from file1.txt which are present in both file2.txt and file3.txt based on column 2 and column ...
2
votes
2answers
42 views

bash + how to define array variable with instance number

Is it possible to define variable that is called for example machine1 as machine$counter ( while counter=1 ) ? For example, I created the /tmp/config.txt file and set the machine1 as array: $ more ...