China DOS Union

Use sed to delete blank lines made up of spaces

Seems like it doesn't do anything

Originally posted by amio at 2008-7-13 12:52:
Seems like it doesn't do anything

What do you mean by “seems like”?
Did you test it?
Why does it test fine for me。。。

sed -i "/^ *$/d" a.txt|find /v ""

This is how I tested it

If you wanted to modify the source file directly, then you should have made that clear in the first post.。
Nope.

Originally posted by HAT at 2008-7-13 02:38 PM:
@echo off sed "/^ *$/d" a.txt>b.txt move /y b.txt a.txt

Did you test whether this works? Why doesn't mine work then?

The OP is really something, just one sentence saying it doesn't work.
What exactly is the problem, and where doesn't it work? Are you really that stingy? Can't even bear to describe what happens when it doesn't work?
People are trying to help you, don't act like they're the ones begging you。。。

I tested it, and it works.
Maybe your sed version is too old.

C:\Test>C:\ProgramMy\GnuWin32\sed --version
GNU sed version 4.1.5
Copyright (C) 2003 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE,
to the extent permitted by law.

Sorry, I got it wrong. What I meant was deleting the spaces at the beginning of a line. Delete only the leading spaces, but keep the text after them.

For example:
aaaaaaaaaaa
becomes
aaaaaaaaaaa

@echo off sed "s/^ *//g" a.txt>b.txt move /y b.txt a.txt
Next time when asking a question, it's best to give an example right in the first post, hehe.

Could it really be a sed version issue? Doesn't HAT's sed need find for filtering?
: @echo off sed "s/^ *//g" a.txt|find /v "">b.txt move /y b.txt a.txt

This was given on the CU forum. Does it mean the same thing?
sed 's/^[[:blank:]]\+//'

If you've lurked on CU long enough, then you'd know that [[:blank:]] includes not only spaces, but all blank characters, hehe.