How to match regexp with ash?

Question

Following code works for bash but now i need it for busybox ash , which apparrently does not have "=~"

keyword="^Cookie: (.*)$"
if [[ $line =~ $keyword ]]
then
bla bla
fi

Is there a suitable replacement ?

Sorry if this is SuperUser question, could not decide.

Edit: There is also no grep,sed,awk etc. I need pure ash.

Wow, no POSIX. Just out of curiosity, what system are you running on? — Ciro Santilli OurBigBook.com, Jan 09 '14 at 07:37

Ciro Santilli OurBigBook.com · Accepted Answer · 2014-08-15T14:14:37.470

4

For this particular regex you might get away with a parameter expansion hack:

if [ "$line" = "Cookie: ${line#Cookie: }" ]; then
    echo a
fi

Or a pattern matching notation + case hack:

case "$line" in
    "Cookie: "*)
        echo a
    ;;
    *)
    ;;
esac

However those solutions are strictly less powerful than regexes because they have no real Kleene star * (only .*) and you should really get some more powerful tools (a real programming language like Python?) installed on that system or you will suffer.

edited Aug 15 '14 at 14:14

answered Jan 09 '14 at 07:27

Ciro Santilli OurBigBook.com

347,512
102
1,199
985

Thanks this works. As you say it is very limited though. It is a router with very little space cant install perl or python. Might try C. – user3155036 Jan 09 '14 at 16:46

score 4 · Answer 2 · answered Dec 16 '19 at 15:10

4

What worked for me was using Busy Box's implementations for grep and wc:

MATCHES=`echo "$BRANCH" | grep -iE '^(master|release)' | wc -l`
if [ $MATCHES -eq 0 ]; then
 echo 'Not on master or release branch'
fi

answered Dec 16 '19 at 15:10

Richard Nienaber

10,324
6
55
66

score 3 · Answer 3 · answered Mar 25 '15 at 08:15

3

Busybox comes with an expr applet which can do regex matching (anchored to the beginning of a string). If the regex matches, its return code will be 0. Example:

 # expr "abc" : "[ab]*"
 # echo $?
 0
 # expr "abc" : "[d]*"
 # echo $?
 1

answered Mar 25 '15 at 08:15

Alex D

29,755
7
80
126

How to match regexp with ash?

3 Answers3

Linked