Linux Shell, Awk: merge 2 variable data per column

The left part data (in variable) like : echo "$lpart" "2017-07-03 13:39:5", "-39dB", "7c:e9:d3:f1:61:55" "2017-07-03 13:39:5", "-39dB", "7c:e9:d3:f1:61:55" "2017-07-03 13:39:5"

Reading a line and assigning a default value to variables in BASH

How do I read a row of data and assign them to variables while also giving them default values? I wanted to achieve something like this, but can't get the syntax right. { read variable1=${variable1:=default1} variable2=${variable2:=default2} read var

How to generate a new terminal and execute a command on it using a shell script?

I want to run a set of commands out of which some I want to run simultaneously in another terminal using shelll script. Let's say I have the below four commands command1 command2 command3 command4 First I want to start command1 in terminal 1 & while

Run a built-in shell function in a script read with chat

#!/usr/bin/env bash function foo(){ param=$1 echo "$param" } content="calling this one with param: $(foo 'this is test param1')" echo "$content" result: calling this one with param: this is test param1 Notice that foo is call

grep, how to search for an exact pattern?

This was what I have tried grep -n 'qtrain' *.m But I got also SKSC.m:195:model.qtrain = model.qtrainExtra(:,k-1); SKSC.m:196:model.mqtrain = model.mqtrainExtra{k-1}; SKSC.m:197:model.sqtrain = model.sqtrainExtra{k-1}; How to get rid of the others? I

Check the execution status of a background process launched from the same bash script

I have to write a bash script that launches a process in background in accordance to command line argument passed and returns if it were successfully able to run launch the program. Here is a pseudo code of what I am trying to achieve if [ "$1"

Script to download a web page

i made a web server to show my page locally, because is located in a place with a poor connection so what i want to do is download the page content and replace the old one, so i made this script running in background but i am not very sure if this wi

Bash - Exclude subdirectories with the find command

This question already has an answer here: How to exclude a directory in find . command 29 answers I'm using the find command to get a list of folders where certain files are located. But because of a permission denied error for certain subdirectories

bash script to perform dig -x

Good day. I was reading another post regarding resolving hostnames to IPs and only using the first IP in the list. I want to do the opposite and used the following script: #!/bin/bash IPLIST="/Users/mymac/Desktop/list2.txt" for IP in 'cat $IPLIS

How to leave a bash function waiting for a return

I'm not completely clear on the how/why bash's exit keyword is inconsistant when calling a function that expects a return vs. not expecting a return. For instance, in the following repro: #!/bin/bash exitfunc() { echo "Flag 1" exit } exitfunc ec

Why bash & ldquo; test -n & rdquo; command gives the wrong result for the $ @ (dollar at) position parameter while & ldquo; test -z & rdquo; works?

Using $@ inside a bash test expression gives odd results. Here's a minimal test script to reproduce the issue (among the alternative formulations for the same test which do pass without error): #! /bin/bash # file path: ./bash_weirdness.sh echo "args

check a specific delimiter per line - bash

I want to write a script in bash that handles a file with lines that has 5 columns and i expect the delimiters to be one single space (" "). everything other than that should lead to an error, even more than 1 space. for instance, that line is l

Analyze the JSON array: 'paste' for bash variables?

At first, I parsed an array JSON file with a loop using jshon, but it takes too long. To speed things up, I thought I could return every value of id from every index, repeat with word another type, put these into variables, and finally join them toge

bash approach to facilitate the binary call with a large amount of parameters

Trying to figure out the best way to automate running a command that takes a lot of parameters and changing some of them. Current approach is this: #!/bin/bash # 5 more of these VALUE=42 STUFF=12 CHARLIE=96 # Note that these are not sequential, just

Reads lines from file and writes directly to FIFO, without buffering in RAM

I have a file with very, very long lines. A single line will not fit in memory. I need to process each line separately, so I'd like to write each line to a FIFO node, sending EOF between lines. This model works well for what I'm doing, and would be i

Where to put shell script / function? .bashrc or bin?

I am learning Linux commands and I learnt that you can write a shell script and put in a customized directory (e.g. ~/bin/ ) and export to $PATH or you can write it as a shell function and put in .bashrc file. If I may ask, what is the right situatio

Unix & amp; gnu / linux distributions: possible locations for the 'which' command?

Would like to reference the full path to the which command as an improvement to some shell scripts. Is anyone aware of a standard location for some unix gnu/linux distribution BESIDES /usr/bin/which?which is not a standard part of linux systems. It's

Read the file line by line and perform an action for everyone in bash

I have a text file, it contains a single word on each line. I need a loop in bash to read each line, then perform a command each time it reads a line, using the input from that line as part of the command. I am just not sure of the proper syntax to d

Make 2 ajax request for a bash treatment

I'm making an ajax request which is making bash treatment. Another action in my page uses an ajax request but this one is waiting the end of my first request for making what I'm asking. Do you have any idea for doesn't waiting the end of the first aj

Bash: read lines in a file in a table

This question already has an answer here: Creating an array from a text file in Bash 6 answers I am trying to read a file containing lines into a Bash array. I have tried the following so far: Attempt1 a=( $( cat /path/to/filename ) ) Attempt2 index=

how to extract certain columns from a file and save them to a new file

I have a file which contains lines of data in the following format: a11 a12 a13 a14 a15 a21 a22 a23 a24 a25 a31 a32 a33 a34 a35 a41 a42 a43 a44 a45 . . . what I need is to save this data in a new file with the following format after performing some a

Why does wget give me two different download times?

The last 3 lines of wget -i urls.txt: FINISHED --2012-05-16 12:58:08-- Total wall clock time: 1h 56m 52s Downloaded: 1069 files, 746M in 1h 52m 49s (113 KB/s) There are two different times: 1h 56m 52s 1h 52m 49s Why are they different? What do they s

short date in bash prompt PS1

You can use \d in the your PS1 confuration to display a long date ie. Tues 18 May, but how can I get it to display it in a format like 18.05.2012 for example?Try this: PS1="\$(date +%d.%m.%Y) > " export PS1

How to know if the output of & ldquo; find & quot; command is empty?

I want to return an exit status of 0 if the output is empty and 1 otherwise: find /this/is/a/path/ -name core.* When you say you want it to return a particular number, are you referring to the exit status? If so: [[ -z `find /this/is/a/path/ -name co

How can I escape spaces in $ HOME in a bash script?

I'm trying to run a script which uses my $HOME variable to set things up (it's gitolite, by the way). However, it's failing because I'm on a system where the home directory path has spaces in it. I want to hack the gitolite bash script at a single po

bash script to run in 5 minutes

I just want a bash script to run 5 minutes after it's called. What am I doing wrong? I have the command: /path/to/my/script | at now + 5 min And yet the script runs right away every time.You are executing the script immediately and sending its output

Best / best way to analyze configuration settings in Sh / Bash and php

I got in every php project (around 25!), some sh scripts that help me with routine tasks such as deployment, repo syncronizing, databases exporting/export, etc. The sh scripts are the same for all the projects I manage, so there must be a configurati

How to create a bash script to check the SSH connection?

I am in the process of creating a bash script that would log into the remote machines and create private and public keys. My problem is that the remote machines are not very reliable, and they are not always up. I need a bash script that would check

Makefile for the program running on different machines

I have a C++ program that will run on several machines that use a Network File System. For each of the C++ libraries that my program uses, I installed a version for each machine, under ~/program_files/machinename/libraryname. "machinename" is ob

Why the & ldquo; to & quot; command always warn me that the commands will be executed via sh?

Every time I use the "at" command, I get this message: warning: commands will be executed using /bin/sh What is it trying to warn me about? More importantly, how do I turn the warning off?It serves as a good warning to those of us that don't use