UNIX for Dummies Questions & Answers

I have a file from which I am trying to delete a particular word on a particular line.

Code:

NEW
NEW
/v/engine
NEW
/ifs/list
NEW
/ifs/vdrome
NEW

I am trying to delete the first line only if it contains the word NEW. I am also trying to delete the last line only if it contains the word NEW. I don't want any other lines deleted. I have tried

Code:

sed '1,/NEW/d'

but that deletes more than the first line. I've also tried

Code:

sed '1d'

but I don't care for that command as it would delete even if the word was not NEW.

It is going to be used on multiple files in a script and I need to make sure that no matter what is in between the last NEW and the first NEW are always deleted. And the words on the first and last line will not always be "NEW."

Any ideas?

For these kinds of logical statements I prefer the UNIX awk command since it actually has logical statements...

Code:

$ printf "%s\n" "NEW" "NEW" "/v/engine" "NEW" |
        awk '! (/NEW/ && (NR==1))'
NEW
/v/engine
NEW

$

/NEW/ && (NR==1) would mean "print lines whenever the line matches the regex /NEW/, and NR ( line number ) equals 1". Putting a ! in front negates it, to print lines only when that's false.

You've been close! Try

Code:

sed '/NEW/{1d;$d}' file

Longhand using "sed" on OSX 10.7.5 default bash terminal:-

Code:

Last login: Wed Sep 25 20:44:33 on ttys000
AMIGA:barrywalker~> echo -e -n "NEW\nNEW\n/v/engine\nNEW\n/ifs/list\nNEW\n/ifs/vdrome\nNEW\n" > /tmp/txt
AMIGA:barrywalker~> sed '{1d;$d;}' < /tmp/txt
NEW
/v/engine
NEW
/ifs/list
NEW
/ifs/vdrome
AMIGA:barrywalker~> text=$(sed '{1d;$d;}' < /tmp/txt)
AMIGA:barrywalker~> echo -n "$text"
NEW
/v/engine
NEW
/ifs/list
NEW
/ifs/vdromeAMIGA:barrywalker~> echo "$text"    ####
NEW
/v/engine
NEW
/ifs/list
NEW
/ifs/vdrome
AMIGA:barrywalker~> _

NOTE: Newline is missing at line "####"...

Sorry? Isn't # the comment introducer ...

Hi RudiC...

Yep, it is and was added after the event as a pointer only; however I ran the same
pseudo-script with the " ####" added to check if it entered OK and it did without change.

It was purely to show the missing newline using the "echo -n....." command.

man echo: