Empty lines in input file

[TanyaB]

Hi,
I have a KSH script that read lines from input file and process them one by one:
while read line ; do
##############
done < $ConfigFile

I want to make sure, that input line is not comment (#) or empty line; for comment I've come up with
if echo $line | grep '^\#' >/dev/null ;then
#Comment Line
else
#regular line - process
fi

How can I detect an empty line?
I've tried something like
if echo $line | grep '\^\$' >/dev/null ;then ...
But it didn't worked - it took every line...

 

[SteveR77]

Tanya,

Try changing your grep statement from '\^\$' > /dev/null to

grep '^$' > /dev/null.


Steve

 

[TanyaB]

Thanks !!!!
It works !!!

 

[Salem]

I might try something like this - to remove all the blank and comment lines in one go

egrep -v '^$|^#' $ConfigFile | while read line ; do
  # regular line - process
done

Depends what you mean by a blank line. Some blank lines could consist entirely of spaces and tabs, but would not be caught by that egrep command (though its easy to add).
Additionally,
[tt]hello # this is a comment[/tt]
is not detected either at present, since comments are assumed to begin at the start of a line.

--

 

[PHV]

Another way to ignore comments and empty/blank lines:

tab=`echo "\t\c"`
sed -e 's/#.*$//' -e '/^[ '$tab']*$/d' $ConfigFile |
 while read line
 do
  #regular line - process
 done

Anyway, to test an empty variable:

[ -z "$line" ] && echo empty

Hope This Help
PH.