Split string into array using multi-character delimiter

Question

I need to split a string into an array. My problem is that the delimiter is a 3 character one: _-_

For example:

db2-111_-_oracle12cR1RAC_-_mariadb101

I need to create the following array:

db2-111
oracle12cR1RAC
mariadb101

Similar questions followed this approach:

str="db2-111_-_oracle12cR1RAC_-_mariadb101"
arr=(${str//_-_/ })
echo ${arr[@]}

Even if the array is created, it has been split incorrectly:

db2 
111 
oracle12cR1RAC 
mariadb101

It seems that the "-" character in the first item causes the array's split function to fail.

Can you suggest a fix for it? Thanks.

Related question in case the input also contains line breaks. — Matthias Braun
– Matthias Braun, Commented Dec 31, 2024 at 0:50

chepner · Accepted Answer · 2018-10-10 15:21:34Z

3

If you can, replace the _-_ sequences with another single character that you can use for field splitting. For example,

$ str="db2-111_-_oracle12cR1RAC_-_mariadb101"
$ str2=${str//_-_/#}
$ IFS="#" read -ra arr <<< "$str2"
$ printf '%s\n' "${arr[@]}"
db2-111
oracle12cR1RAC
mariadb101

answered Oct 10, 2018 at 15:21

chepner

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Comments

Aserre · Accepted Answer · 2018-10-10 15:39:14Z

2

You could use sed to do what you want, i.e. writting something like that :

str="db2-111_-_oracle12cR1RAC_-_mariadb101"
arr=($(sed 's/_-_/ /g' <<< $str))
echo ${arr[0]}

Edit :

The reason arr=(${str//_-_/ }) didn't work is that when you write it like that, everything inside ${ ... } is considered as 1 element of the array. So, using sed, or even simply arr=($(echo ${str//_-_/ })) will produce the result you expect.

edited Oct 10, 2018 at 15:39

answered Oct 10, 2018 at 15:17

Aserre

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6 Comments

Francesco Marchioni Over a year ago

Thanks for the suggestion. I've tried it though and it produces a 1 sized array unfortunately: echo ${arr[0]} db2 111 oracle12cR1RAC mariadb101

Francesco Marchioni Over a year ago

Using escapes didn't work either sed "s/\_\-\_/ /g"

Aserre Over a year ago

Are you sure you are using the exact code I gave? Copy/pasting my code works on zsh, bash-4.4 and bash-3.2 on my computer (using GNU sed)

Francesco Marchioni Over a year ago

Indeed a bit weird. The code is the same. I'm running bash 4.3.43(1) release

chepner Over a year ago

@FrancescoMarchioni That's the output you'll get in bash 4.3 if you have IFS="_-_", which seems like something you might have tried and forgot to reset. This code assumes that IFS has its default value.

|

RARE Kpop Manifesto · Accepted Answer · 2022-05-28 21:15:56Z

2

<<<'db2-111_-_oracle12cR1RAC_-_mariadb101' | 

{m,g}awk NF=NF FS='_[-]_' OFS='\n'

db2-111
oracle12cR1RAC
mariadb101

if you like the fringe but ultra concise RS syntax, it's

mawk ~ RS='_-_|\n'

   or

mawk \$_ RS='_-_|\n'

   or simply

mawk RS RS='_-_|\n'

db2-111
oracle12cR1RAC
mariadb101

edited May 28, 2022 at 21:15

answered May 28, 2022 at 21:09

RARE Kpop Manifesto

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Comments

stack0114106 · Accepted Answer · 2018-10-15 17:45:39Z

0

Using Perl one-liner

$ echo "db2-111_-_oracle12cR1RAC_-_mariadb101" | perl -F/_-_/ -ne ' { print "$F[0]\n$F[1]\n$F[2]" } '
db2-111
oracle12cR1RAC
mariadb101

answered Oct 15, 2018 at 17:45

stack0114106

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Comments

anubhava · Accepted Answer · 2022-05-27 10:28:13Z

0

Here is a solution using replacement of _-_ with a NUL byte since we cannot make a safe assumption that some character like # or ; or : will not be present in input strings.

readarray -d '' arr < <(
   awk -F'_-_' -v OFS='\0' '{ORS=OFS; $1=$1} 1' <<< "$str")

declare -p arr
declare -a arr=([0]="db2-111" [1]="oracle12cR1RAC" [2]="mariadb101")

Note that due to use of readarray it will require BASH ver 4+

edited May 27, 2022 at 10:28

answered May 27, 2022 at 10:23

anubhava

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