How to replace special characters?

UNIX for Advanced & Expert Users
1

Hi Team,

I have data like this.

|*|.5|*|0.2|*|A.B|*|

Would like to add zero (0) before the decimal point where there is no zero as

|*|0.5|*|0.2|*|A.B|*|

How to replace ||. with ||0.

I tried below command which didn't work

echo '|*|.5|*|0.2|*|A.B|*' | sed 's/\|\*\|\./\|\*\|0\./g'

Thanks...

2 
$ echo '|*|.5|*|0.2|*|A.B|*|' | sed 's/|\./|0\./'
|*|0.5|*|0.2|*|A.B|*|
3

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4

Why use sed?
Longhand using OSX 10.12.4, default bash terminal.
(Assumption bash is available.)
Interactive mode is a great way to test.

Last login: Fri Apr 21 22:35:25 on ttys000
AMIGA:amiga~> STRING='|*|.5|*|0.2|*|A.B|*|'
AMIGA:amiga~> PREFIX="|*|0"
AMIGA:amiga~> echo "$PREFIX${STRING:3}"
|*|0.5|*|0.2|*|A.B|*|
AMIGA:amiga~> _
1 Like
5

Post#4 requires the match at the beginning of the string.
Post#2 does only one substitution and also does it for A.B .
The following requires a digit after the dot, and because it is part of the match must mark it in \( \) and put it back via a back-reference. Also it does the substitution globally.

echo '|*|.5|*|0.2|*|A.B|*|' | sed 's/|\(\.[0-9]\)/|0\1/g'