string substitution

lipun4u · 02-22-2010, 01:50 AM

I was reading string substitution...

str=abcABC123ABCabc

echo ${str#a*C}
echo ${str##a*C}

Can somebody explain me how it works ??

micxz · 02-22-2010, 02:03 AM

Code:

str=abcABC123ABCabc
#   |----|          shortest
#   |----------|    longest

echo ${str#a*C} # 123ABCabc
# Strip out shortest match between 'a' and 'C'.

echo ${str##a*C} # abc
# Strip out longest match between 'a' and 'C'.

quote from abs guide'

neonsignal · 02-22-2010, 02:05 AM

Both of these are string deletions. The expression that follows the # is the pattern that is being matched (and deleted), in this case 'a*C'. In other words, the pattern is 'a', followed by 0 or more characters, followed by a 'C'.

The difference between the two examples is that the first does a minimal match (ie, finds the match from the start of the string that is the shortest), while the second does a maximal match (ie, finds the match from the start of the string that is the longest).

micxz · 02-22-2010, 02:19 AM

reading this again I think I just quoted what your reading. So thanks to neonsignal its explained. strip out is the key word here. I hope you got it now'