On Wednesday, 23 January 2019 2:32:43 PM AEDT Adam Carter wrote: > > $ printf '0.1.2.3 01.2.3.4 1.2.3.0 1.2.000.3\n' | \ > > > > sed 's/0*\([[:digit:]]\+\)/\1/g' > > > > 0.1.2.3 1.2.3.4 1.2.3.0 1.2.0.3 > > Hi David - thanks for that. > > So [[:digit:]] is another way of writing [0-9] and the + just means another > instance of the proceeding expression, right, so your and Francois > solutions are functionally the same, and all the following are the same > too, right? > > [[:digit:]]+ > [[:digit:]][[:digit:]] > [0-9]+ > [0-9][0-9]
Not quite. A trailing '+' means "1 or more of the preceding item", while a trailing '*' means "0 or more". [0-9]+ would match any string consisting of only digits, no matter how long, but not an empty string. -- Reverend Paul Colquhoun, ULC. http://andor.dropbear.id.au/ Asking for technical help in newsgroups? Read this first: http://catb.org/~esr/faqs/smart-questions.html#intro
