l38.2a

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 2A 代码 · 共 26 行

#print
Sometimes you want to recognize a string of characters
only if they appear at the beginning of the line.
The character '^' is used for this purpose.  The
command
  s/^ab/xy/
will change "ab" to "xy" only if "ab" begins the line.
Try the following and watch what it does.

ex file
1,2p
1,2s/^ab/xy/
wq
ready
#create Ref
xycd
  abcd
#create file
abcd
  abcd
#user
#cmp file Ref
#log
#next
38.2b  5