While searching for a unix problem, I came across the following string splitting regular expression statement:
string="[email protected];[email protected];[email protected]"
str1=${string%%;*}
str2=${string##*;}
Result:
[email protected]
[email protected]
I did not understand the second expression(str2). Can please someone help.
Thanks
From the bash manual, under Parameter Expansion:
${parameter#word}
${parameter##word}
The word is expanded to produce a pattern just as in pathname expansion. If the pattern matches the beginning of the
value of parameter, then the result of the expansion is the expanded value of parameter with the shortest matching pat-
tern (the ``#'' case) or the longest matching pattern (the ``##'' case) deleted. If parameter is @ or *, the pattern
removal operation is applied to each positional parameter in turn, and the expansion is the resultant list. If parameter
is an array variable subscripted with @ or *, the pattern removal operation is applied to each member of the array in
turn, and the expansion is the resultant list.
${parameter%word}
${parameter%%word}
The word is expanded to produce a pattern just as in pathname expansion. If the pattern matches a trailing portion of
the expanded value of parameter, then the result of the expansion is the expanded value of parameter with the shortest
matching pattern (the ``%'' case) or the longest matching pattern (the ``%%'' case) deleted. If parameter is @ or *, the
pattern removal operation is applied to each positional parameter in turn, and the expansion is the resultant list. If
parameter is an array variable subscripted with @ or *, the pattern removal operation is applied to each member of the
array in turn, and the expansion is the resultant list.
