UNIX for Dummies Questions & Answers

In my bash script I want to echo lines in a file and ensure no blank lines are echoed:

Code:

for i in $(cat txt)
do
echo $i | sed 's/|/ /g;s/ SEARCHTERM$//g;s/ /\r\n/g;s/^$/d'
done

Keep in mind this is a fragment so ignore the fact that the for loop is not closed. When I add the "s/^$/d' per several other examples I've found on these forums I receive an "unterminated s" error. How do I properly remove blank lines? I tried removing the s and breaking it into a separate sed statement but either it's not removing the blank lines or I get an unterminated s error. Sample input file is UNIX GID's from the /etc/group file, one per line.

Hi MaindotC,

You have a mix between the selection command

Code:

/.../

and substitute command

Code:

s/.../.../

Use:

Code:

/^$/ d

I'm still getting blank lines I tried adding it at the end of my sed statement as well as piping it into another sed expression. Removed the "s" - still blank lines.

There are lots of ways to do this depending on what tools you're using to process the lines that aren't empty. But, for what it looks like you're trying to do with this script, you could use:

Code:

grep . txt

or if you really want to use sed:

Code:

sed '/^$/d' txt

Blank lines might not be empty lines (immediate newline), but have one or more whitespace characters between the beginning of the line and the newline. Does this help?

Code:

sed  -E '/^[[:space:]]*$/ d' input-file >output-file

Code:

awk 'NF' yourfile.txt

This is really weird...I modified my sed expression:[code]for i in $(cat txt)
do
echo $i | sed 's/|/ /g;s/ SEARCHTERM$//g;s/ /\r\n/g;/^[[:space:]]*$/ d;/^$/d'
done[/code
I tried adding the -E but I got a lot of error messages - not sure why that was included. So most of the whitespaces are gone...there used to be 5 whitespaces, now there is 1. So based on this information I have to assume there's something freaky going on with my input file?

---------- Post updated at 03:10 PM ---------- Previous update was at 03:09 PM ----------

Close, but I'm still getting some whitespaces. Possibly an issue with the input file? Anyway I can view special, hidden chars?