shell – IT Nursery

How to preserve line breaks when storing command output to a variable?

June 4, 2022 by IT Nursery

I’m using bash shell on Linux. I have this simple script … #!/bin/bash TEMP=`sed -n “https://stackoverflow.com/””Starting deployment of”‘/,/'”Failed to start context”‘/p’ “/usr/java/jboss/standalone/log/server.log” | tac | awk “https://stackoverflow.com/””Starting deployment of”‘/ {print;exit} 1’ | tac` echo $TEMP However, when I run this script ./temp.sh all the output is printed without the carriage returns/new lines. Not sure if … Read more

Run a string as a command within a Bash script

June 4, 2022 by IT Nursery

I have a Bash script that builds a string to run as a command Script: #! /bin/bash matchdir=”/home/joao/robocup/runner_workdir/matches/testmatch/” teamAComm=”`pwd`/a.sh” teamBComm=”`pwd`/b.sh” include=”`pwd`/server_official.conf” serverbin=’/usr/local/bin/rcssserver’ cd $matchdir illcommando=”$serverbin include=”$include” server::team_l_start=”${teamAComm}” server::team_r_start=”${teamBComm}” CSVSaver::save=”true” CSVSaver::filename=”out.csv”” echo “running: $illcommando” # $illcommando > server-output.log 2> server-error.log $illcommando which does not seem to supply the arguments correctly to the $serverbin. Script output: running: … Read more

How do I delete/remove a shell function?

June 3, 2022 by IT Nursery

I have done this: $ z() { echo ‘hello world’; } How do I get rid of it? 2 Answers 2

Print a file’s last modified date in Bash

June 3, 2022 by IT Nursery

I can’t seem to find how to print out the date of a file. I’m so far able to print out all the files in a directory, but I need to print out the dates with it. I know I need to attach a date format with the echo of the entry, but all I … Read more

The ‘eval’ command in Bash and its typical uses

June 3, 2022 by IT Nursery

After reading the Bash man pages and with respect to this post, I am still having trouble understanding what exactly the eval command does and which would be its typical uses. For example, if we do: $ set — one two three # Sets $1 $2 $3 $ echo $1 one $ n=1 $ echo … Read more

List files with certain extensions with ls and grep

June 3, 2022 by IT Nursery

I just want to get the files from the current dir and only output .mp4 .mp3 .exe files nothing else. So I thought I could just do this: ls | grep \.mp4$ | grep \.mp3$ | grep \.exe$ But no, as the first grep will output just mp4’s therefor the other 2 grep’s won’t be … Read more

How to set child process’ environment variable in Makefile

June 3, 2022 by IT Nursery

I would like to change this Makefile: SHELL := /bin/bash PATH := node_modules/.bin:$(PATH) boot: @supervisor \ –harmony \ –watch etc,lib \ –extensions js,json \ –no-restart-on error \ lib test: NODE_ENV=test mocha \ –harmony \ –reporter spec \ test clean: @rm -rf node_modules .PHONY: test clean to: SHELL := /bin/bash PATH := node_modules/.bin:$(PATH) boot: @supervisor \ … Read more

How to merge 2 JSON objects from 2 files using jq?

June 2, 2022 by IT Nursery

I’m using the jq tools (jq-json-processor) in shell script to parse json. I’ve got 2 json files and want to merge them into one unique file Here the content of files: file1 { “value1”: 200, “timestamp”: 1382461861, “value”: { “aaa”: { “value1”: “v1”, “value2”: “v2” }, “bbb”: { “value1”: “v1”, “value2”: “v2” }, “ccc”: { … Read more

How to use sed to remove the last n lines of a file

June 2, 2022 by IT Nursery

I want to remove some n lines from the end of a file. Can this be done using sed? For example, to remove lines from 2 to 4, I can use $ sed ‘2,4d’ file But I don’t know the line numbers. I can delete the last line using $sed $d file but I want … Read more

How to get the part of a file after the first line that matches a regular expression

June 2, 2022 by IT Nursery

I have a file with about 1000 lines. I want the part of my file after the line which matches my grep statement. That is: cat file | grep ‘TERMINATE’ # It is found on line 534 So, I want the file from line 535 to line 1000 for further processing. How can I do … Read more