How to split string into component parts in Linux Bash/Shell

Question

I'm writing the second version of my post-receive git hook.

I have a GL_REPO variable which conforms to:

/project.name/vhost-type/versioncodename

It may or may not have a trailing and/or preceding slash.

My current code misunderstood the function of the following code, and as a result it clearly duplicates $versioncodename into each variable:

# regex out project codename
PROJECT_NAME=${GL_REPO##*/}
echo "project codename is: $PROJECT_NAME"

# extract server target vhost-type -fix required
VHOST_TYPE=${GL_REPO##*/}
echo "server target is: $VHOST_TYPE"

# get server project - fix required
PROJECT_CODENAME=${GL_REPO##*/}
echo "server project is: $PROJECT_CODENAME"

What is the correct method for taking these elements one at a time from the back of the string, or guaranteeing that a three part string allocates these variables?

I guess it might be better to split into an array?

Community · Accepted Answer · 2017-05-23 11:52:17Z

9

#!/bin/bash

GL_REPO=/project.name/vhost-type/versioncodename
GL_REPO=${GL_REPO#/} # remove preceding slash, if any

IFS=/ read -a arr <<< "$GL_REPO"

PROJECT_NAME="${arr[0]}"
VHOST_TYPE="${arr[1]}"
PROJECT_CODENAME="${arr[2]}"

^{UPDATE: an alternative solution by anishsane:}

IFS=/ read PROJECT_NAME VHOST_TYPE PROJECT_CODENAME <<< "$GL_REPO"

edited May 23, 2017 at 11:52

CommunityBot

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answered Jul 3, 2015 at 11:14

Eugeniu Rosca

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5 Comments

anishsane Over a year ago

I was going to answer exactly this. +1. Clean & simple.

anishsane Over a year ago

Alternately IFS=/ read PROJECT_NAME VHOST_TYPE PROJECT_CODENAME <<< "$GL_REPO"

Felkja Over a year ago

Hi I used your solution in the end

Eugeniu Rosca Over a year ago

@anishsane: looks great. I have updated my answer with your solution. user3706702: thanks

Felkja Over a year ago

@anishine my thanks was removed from the solution due to editing, so just to be sure I am grateful to everyone who helped including Euginiu Rosca, and several other good solutions to this problem

AlBlue · Accepted Answer · 2015-07-03 11:19:10Z

2

You can use cut with a field separator to pull out items by order:

NAME=$(echo $GL_REPO | cut -d / -f 1)

You can repeat the same for other fields. The trailing/leading slash you can ignore (you'll get a NAME field being empty, for example) or you can strip off a leading slash with ${GL_REPO##/} (similarly, you can strip off a trailing slash with ${GL_REPO%%/}).

answered Jul 3, 2015 at 11:19

AlBlue

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1 Comment

Felkja Over a year ago

Hi thanks. I used part of your solution in resolving the problem to make sure both ends had the slashes removed

Jahid · Accepted Answer · 2015-07-03 14:17:53Z

1

This is another way:

GL_REPO="/project.name/vhost-type/versioncodename"
GL_REPO="${GL_REPO/#\//}" 
#^replace preceding slash (if any) with empty string.
IFS="/" arr=($GL_REPO)
echo "PN: ${arr[0]} VHT: ${arr[1]} VC: ${arr[2]}"

Using Bash Pattern Matching:

GL_REPO="/project.name/vhost-type/versioncodename"
patt="([^/]+)/([^/]+)/([^/]+)"
[[ $GL_REPO =~ $patt ]]
echo "PN: ${BASH_REMATCH[1]} VHT: ${BASH_REMATCH[2]} VC: ${BASH_REMATCH[3]}"

edited Jul 3, 2015 at 14:17

answered Jul 3, 2015 at 13:48

Jahid

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