sub string search bash scripting

Question

When given a string I want to search for a substring which matches two characters (9&0. 0 should be the last character in that substring) and exactly two characters in between them

string="asd20 92x0x 72x0 YX92s0 0xx0 92x0x"
#I want to select substring YX92s0 from that above string

for var in $string
do
if [[ "$var" == *9**0 ]]; then
    echo $var  // Should print YX92s0 only
fi
done

Obviously this above command doesn't work.

chepner · Accepted Answer · 2013-03-18 21:58:55Z

1

You match each element against the pattern *9??0. There are several ways you can do this; here's one that uses the string to set the positional parameters in a subshell, then iterates over them in a for loop:

( set -- $string
  for elt; do [[ $elt == *9??0 ]] && { echo "found"; exit; }; done )

answered Mar 18, 2013 at 21:58

chepner

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1 Comment

yalkris Over a year ago

Sorry I missed to add for loop in my original question. There was one actually. My question was about the search pattern. When I changed my pattern *9**0 to *9??0 that if condition worked just fine :). Thanks

Gilles Quénot · Accepted Answer · 2013-03-18 22:49:39Z

0

string="asd20 92x0x 72x0 X92s0 0xx0"

if [[ $string =~ [[:space:]].?9.{2}0[[:space:]] ]]; then
    echo "found"
fi

Or better, taking advantage of word spliting :

string="asd20 92x0x 72x0 X92s0 0xx0"

for s in $string; do
    if [[ $s =~ (.*9.{2}0) ]]; then
        echo "${BASH_REMATCH[1]} found"
    fi
done

This is regex with bash.

edited Mar 18, 2013 at 22:49

answered Mar 18, 2013 at 21:30

Gilles Quénot

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5 Comments

yalkris Over a year ago

This solution didn't work on string "X9xx0 9xx0x". It returned 9xx0x instead of X9xx0

Gilles Quénot Over a year ago

copy/paste one more time, post edited accordingly. I've made the assumtion that there's only one character or nothing between the leading space and the 9 digit

Scrutinizer Over a year ago

IMO the second solution would need a $-anchor.

yalkris Over a year ago

I was using a for loop like your second solution.. that regex didn't work on "x9xx0 9xx0x". It selected 9xx0x instead of wanted x9xx0

yalkris Over a year ago

for s in $string; do if [[ $s == *9??0 ]]; then echo $s; fi done WORKED FINE :)

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