remove particular characters from a variable using bash

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I want to parse a variable (in my case it's development kit version) to make it dot(.) free. If version='2.3.3', desired output is 233. I tried as below, but it requires . to be replaced with another character giving me 2_3_3. It would have been fine if tr . '' would have worked. 1 VERSION='2.3.3' 2 echo "2.3.3" | tr . _ bash text-processing shareimprove this question asked Dec 12 '13 at 14:51 Prayag Upd 52631026

2   No, it doesn't require: echo "2.3.3" | tr -d .. – manatwork Dec 12 '13 at 14:59  @manatwork Great, that works. You can post it as answer. Thanks – Prayag Upd Dec 12 '13 at 15:04 Lot of good answers. But if I can second-guess the objective, be warned about 2.11.3 and 2.1.13... ;-) Consider adding padding zeroes to numbers. – Rmano Dec 12 '13 at 16:06  @Rmano You mean something like VERSION='2.30.3100'? No matter what just .'s are removed with all of the answers here. – Prayag Upd Dec 12 '13 at 16:13  @PrayagUpd --- I simply meant that if you will use the number after the conversion for comparisons (as to say if "is this version newer or the same") you should take care of cases like 2.11.3 and 2.1.13 --- they seems the same after dot removal, but clearly 2.11.3 is newer. Also, 2.11.3 is newer than 2.1.14, but comparing 2113 and 2114 will lead to the wrong answer. I remember a bug somewhere for this... – RmanoDec 12 '13 at 16:19 show 3 more comments

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up vote19down voteaccepted	There is no need to execute an external program. bash's string manipulation can handle it (also available in ksh (where it comes from) and zsh): VERSION='2.3.3' echo "${VERSION//.}" (In those shells' manuals you can find this in the parameter expansion section.) shareimprove this answer edited Dec 12 '13 at 15:34 answered Dec 12 '13 at 15:25 manatwork 14k15071
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up vote10down vote	By chronological order: tr/sed echo "$VERSION" | tr -d . echo "$VERSION" | sed 's/\.//g' csh/tcsh echo $VERSION:as/.// POSIX shells: set -f IFS=. set -- $VERSION IFS= echo "$*" ksh/zsh/bash echo "${VERSION//.}" zsh echo $VERSION:gs/./ shareimprove this answer edited Nov 10 at 21:14 answered Dec 12 '13 at 15:38 Stéphane Chazelas 135k21174344
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you should try with sed instead sed 's/\.//g' shareimprove this answer