topic Re: Delete blanks lines in a text plain file in Operating System - HP-UX

Delete blanks lines in a text plain file

Sergio Bascur — Thu, 18 Feb 2010 20:16:28 GMT

Hi everyone...
You know, I've been looking for any kind of command with sed or awk for deleting blanks lines in a txt file on a HP-UX server.
I already got the filtered file and I found a web page in which they say with the expression "sed '/^$/d'" but this isn´t working for me.
Can anybody help me with this?
Thanks a lot!

Re: Delete blanks lines in a text plain file

Tim Nelson — Thu, 18 Feb 2010 20:21:09 GMT

This works for me..

sed /^$/d my.file

post your error, maybe that will help ?

Re: Delete blanks lines in a text plain file

James R. Ferguson — Thu, 18 Feb 2010 20:48:03 GMT

Hi:

# perl -pi.old -e 's/^\s*$//' file

...will eliminate all blank lines from your file after creating a backup copy suffixed with ".old".

This works for lines that consist only of a newline or lines that have leading spaces and/or tab characters only.

Regards!

...JRF...

Re: Delete blanks lines in a text plain file

Hakki Aydin Ucar — Thu, 18 Feb 2010 21:19:28 GMT

Hi,

# sed '/^$/d' testfile # Delete blank Line from a file using sed

Re: Delete blanks lines in a text plain file

James R. Ferguson — Thu, 18 Feb 2010 21:32:56 GMT

Hi (again):

To be clear:

# sed /^$/d file

...will *not* delete "blank" lines unless those lines consist *only* of a newline character --- without leading whitespace.

The Perl snippet I suggested works both for lines that consist only of a newline or lines that have leading spaces and/or tab characters only before the final newline character.

If you insist on 'sed', this mimics the Perl snippet albeit without the inplace file modication:

# sed -e '/^[ ]*$/d' file

Notice carefully that the characters between the square brackets are really a blank and a tab. HP-UX's 'sed' doesn't allow metacharacters like '\t' to a tab. HP-UX's 'sed' doesn't allow inplace modification, either.

Regards!

...JRF...

Re: Delete blanks lines in a text plain file

Patrick Wallek — Thu, 18 Feb 2010 21:38:36 GMT

This will work as well:

sed '/^[[:space:]]*$/d'

And it has the benefit of being easier to read than the brackets with a and a character between them.

Re: Delete blanks lines in a text plain file

Bill Hassell — Fri, 19 Feb 2010 02:27:04 GMT

The shortest solution:

awk NF data.txt

This handles zero length lines, spaces and tabs -- any number on the blank lines.

Re: Delete blanks lines in a text plain file

R.K. # — Fri, 19 Feb 2010 03:24:13 GMT

Hi Sergio,

>> any kind of command with sed or awk
You got great answers for sed/awk. In case you look for anything else, try this:

# more filename | grep -v ^$

Regds..

Re: Delete blanks lines in a text plain file

Dennis Handly — Fri, 19 Feb 2010 03:34:11 GMT

>RK: more filename | grep -v ^$

Not sure why you want more(1) involved?
(Unless you want to use -s to give grep a head start? :-)
Just use: grep -v ^$ filename
Or: grep -v '^[[:space:]]*$' filename

Re: Delete blanks lines in a text plain file

Patrick Wallek — Fri, 19 Feb 2010 03:37:06 GMT

>># more filename | grep -v ^$

This will have the same problem as the initial 'sed' statement posted. It will only match lines that consist of a "newline" character ONLY. If there are spaces and/or tabs on the line that will not work.

To take care of spaces and/or tabs you would have to do:

# more filename | grep -v ^[[:space:]]*$

or, even easier with spawning a unnecessary "more" process:

# grep -v ^[[:space:]]*$ filename

Re: Delete blanks lines in a text plain file

R.K. # — Fri, 19 Feb 2010 04:28:46 GMT

Thanks Dennis and Patrick, I will surely go through these differences.