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

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2
votes
3answers
794 views

How to sort data in the file using script?

I have a file logs.txt with numbers which repeat: 1 QWE 1 ASD 1 QWE 1 QWE 1 QWE 1 qwe 12 22 qwe 2 aaa 2 vcc 2 xxx 4 asa 44 qwe 4 gfd 4 bcx 5 6 kuy 7 76 lol 5 4 ggg 23 ...
1
vote
0answers
46 views

How can you recover from disk corruption on a backup drive whilst maintaining all hard links?

So, I have a scenario that is similar to How to copy directories with preserving hardlinks? that I wish to use however I have corruption from the backup hardlink source. My Scenario: 1. I backup my ...
8
votes
2answers
726 views

Multiple shebangs in a single bash file

I have a script from other person which has a look (note: it's a single file): #!/bin/bash some commands some commands #!/bin/bash some commands some commands #!/bin/bash some commands some ...
2
votes
2answers
117 views

Selecting a random sample from a directory tree

I've got a directory that contains directories that contain directories that contain files. I'd like to select two files at random from each leaf directory. I found this question about selecting ...
2
votes
1answer
398 views

Batch Extract & Repack .RAR Files

I'm dealing with a large amount of password protected .rar files which need to be repacked to remove the password. (The password is known.) I was wondering if there was a script to batch/recursively ...
2
votes
2answers
284 views

Remove first n lines from file with variable

The command below works for deleting the first 3 lines: sed -i -e 1,3d t.txt So I tried substituting the 3 with a variable in a script as below NrLines=$(wc -l t.txt) sed -i -e 1,"$NrLines{d}" ...
2
votes
1answer
802 views

For Loop for Google Image Downloading Bash Script

I have a bash script which downloads images from Google Images. This is the command I use: bash getimages.sh 3 rocky%20mountains That command will download the 3rd picture in Google Images. To ...
4
votes
6answers
719 views

Extracting lines based on conditions

Each line in a comma-separated file has 5 fields. a,b,c,d,e f,g,c,i, j,k,c,m,n o,p,c,r,s t,u,c,w, x,y,z,aa,bb How can I extract the lines which have c in the 3rd field and their 5th field is NOT ...
3
votes
1answer
479 views

How do I rename many files from whatever to sequential filenames? [duplicate]

I have a directory with 8,000 images. These have a variety of filenames and are of type jpeg or png. I want to rename them to: pic00001.png pic00002.jpg I don't mind if I end up doing the pngs in ...
1
vote
3answers
187 views

Script to move one filetype and create a subfolder, if it exists?

I'm trying to find a script that would basically look recusively at a directory, and if the script finds file that are .flac files, it will create a subfolder called FLAC in that same folder, and move ...
0
votes
1answer
71 views

Modification needs to be done in iptables in case of a bridge between two interfaces is implemented

I have a machine with 2 NICs; eth0 and eth1. Each NIC has an assigned IP address and the traffic between them is controlled using the below script. #!/bin/bash SAT_RECV="192.168.200.0/16" NQ=9 ...
2
votes
2answers
298 views

CRON Job To Execute Command On Low Memory

I have a situation where I may need to execute an SAP command line tool hdbsql when memory gets too low (to help clean out the HANA table cache). I'm not well versed in Unix/Linux, and was wondering ...
2
votes
2answers
226 views

bash: can't set a variable to a solid string [duplicate]

I cannot set a variable with a whole command-string as following: A="/bin/ps wwwaux" for a in $A do echo "$a" done It assigns array instead of solid string somewhy. Could you assist, please. My ...
0
votes
2answers
114 views

How to turn Diff command into bash script with prompt

I have a list that i've copy and i want to paste it to the shell to give me just the repeated lines. 1 1 3 2 As i read about bash commands i've maded this: cat > /tmp/sortme ...
2
votes
1answer
379 views

Task not run by crontab

crontab strangely does not execute my script, although the script is running just fine from the shell terminal. I already made sure that scripts are separated from each other by a new line space. ...
1
vote
2answers
71 views

Alignment when printing a series of records

How can I resolve the problem of the tables going to the right. I just want it to be shown under 1. Here's my script with START added. The alignment has gone wonky now: while IFS="," read f1 f2 f3 ...
10
votes
1answer
1k views

Know which process does I/O without iotop

On Linux, I want to know which process uses my disk I/O bandwith. I know I can use iotop but I have a machine where, for various reasons, iotop cannot be installed. How can I manually get that ...
0
votes
0answers
34 views

awk search for string containing forward slash in variable [duplicate]

I'm searching for a string in a massive XML file. Snip: <sv:node sv:name="notfound"> <sv:property sv:name="jcr:primaryType" sv:type="Name"> ...
2
votes
2answers
51 views

sed replace after matching character

I have to change a properties file containing the property: ro.product.firmware=0.0.1 with a new value that is coming from a function called in a different section of my bash script. I cannot get ...
1
vote
3answers
5k views

Script to check if file exists and copy

Pretty new to shell script, want to write script which checks if any file .300 extension exists on /exports/files on server 10.xx.xx.xx. If *.300 exists, move file to /exports/files/arch and send an ...
-1
votes
1answer
76 views

How to duplicate lines in a text (xpm) file?

I'm having some pixmaps like this (36, to be exact): /* XPM */ static char * hide_active_xpm[] = { "12 14 3 1", " c None", ". c #EDEDED s active_color_2", "+ c #313739 s active_text_color_2", " ...
3
votes
3answers
118 views

How can I count the number of times a phrase appears in a file, and format it neatly?

I have a log file I am trying to pull data from. It is formatted like so, and lists when certain modules are checked in and out: 19:50:26 (license_manager) OUT: "certain_module" doej@server.domain ...
1
vote
1answer
215 views

Why does bash try to execute strings in a string substitution?

My script is supposed to take input from a pipe and replace newline characters with commas, using the bash's string substitution: #! /bin/bash read -d -r input echo $input $input=${input//\n/,} ...
2
votes
3answers
130 views

Find the complement set of an array?

Following from this question, where I wish to extract 10 random lines from a file, I now wish to also have the remaining 90 lines as a separate file. Since the document has 100 lines, indexing from 1 ...
1
vote
2answers
53 views

Re-print an array in a certain format?

I wish to take 10 random lines of file, which is 100 lines long. First, I randomly generate 10 integers between 1 and 100 (inclusive) with ind=$(shuf -i 1-100 -n 10 | sort -n) Then, I wish to use ...
3
votes
3answers
422 views

Specific column level substitution

If I have a file with columnar entries, is it possible to substitute specific entries from a specific columns only and save changes to the same file?? Example a file abc.txt: SR|FRUITS|COLOR| ...
1
vote
2answers
83 views

Substrings in shell script

Am trying to get a substring from a string but am getting the error: ${curr_rec:3:4}: bad substitution #!/bin/ksh get_file_totals() { if [ -e "$file_name" ] then IFS='' ...
1
vote
1answer
65 views

In ShellScript, how to call a function after completion of function which is already running?

My script involves three shell functions. Two running in parallel. I have to call a third function when the two parallel running function completes it's execution. How to call that third function? ...
2
votes
1answer
98 views

POSIX shell scripting and performance tuning [closed]

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
101 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 ...
3
votes
1answer
217 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
108 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 ...
7
votes
4answers
757 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
262 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 = ...
1
vote
5answers
1k 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
443 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
2k 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
vote
3answers
731 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 ...
1
vote
1answer
362 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
4answers
944 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 `'' ...
5
votes
4answers
3k 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
1answer
239 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
339 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
118 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?
4
votes
3answers
305 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
150 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 ...
2
votes
2answers
828 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 ...
5
votes
1answer
272 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
votes
1answer
278 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
747 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 ...