[unix-history] / usr / lib / learn / editor / L35.2d

#print
A useful operation is to replace a string of several blanks
by exactly one blank.  Note that you can't just write

s/ */ /

because the " *" willl match any number of blanks
including zero.  Thus it will always match at the beginning
of the line, even if there is no blank there.
The normal sequence is

s/  */ /
which will only substitute for a string
that has at least one blank in it.
Try that command on the line in the file "line".
Then rewrite the file "line" and type "ready".
#create Ref
here is a long space.
#create line
here      is a long space.
#user
#cmp line Ref
#log
#next
35.2e 5
Commit	Line	Data
fed84c9b TL	1	#print
	2	A useful operation is to replace a string of several blanks
	3	by exactly one blank. Note that you can't just write
	4
	5	s/ */ /
	6
	7	because the " *" willl match any number of blanks
	8	including zero. Thus it will always match at the beginning
	9	of the line, even if there is no blank there.
	10	The normal sequence is
	11
	12	s/ */ /
	13	which will only substitute for a string
	14	that has at least one blank in it.
	15	Try that command on the line in the file "line".
	16	Then rewrite the file "line" and type "ready".
	17	#create Ref
	18	here is a long space.
	19	#create line
	20	here is a long space.
	21	#user
	22	#cmp line Ref
	23	#log
	24	#next
	25	35.2e 5