From: qazwart
Date: Thurs, Apr 7 2005 9:20 am
Email: "qazwart" <qazw...@gmail.com>
Groups: comp.unix.shell

Remember that sed has more commands in it than just "s" for
substitution:

sed '/^$/d'

Any line that matches the pattern "/^$/" (blank lines) will be deleted
from the input. If you want to delete lines that may contain spaces and
tabs, but nothing else, you need to use this:

sed '/^[ \t]*$/d

The "\t" doesn't work with all versions of sed, so you might need to
use a real tab character instead.

============================
sed '/^$/d' works, i.e. removes empty lines, but sed '/^[ \t]*$/d' does
not - the lines that have tabs and spaces are still there. I tried
sed '/^[]*$/d' (a real tab between the square brackets)
and
sed '/^*$/d' (a real tab between ^ and *)
and neither works. (The real tab does not show up in the command
line.)

> sed '/^[ \t]*$/d' does not work
Sorry guys, I just found out that
1. I probably missed the space inside the square brackets, and
2. I did not know I need to type a Ctrl-v before typing a real tab in
order for the shell to recognize the tab character
Now it works.
Further, sed 's/[ ]*$//'
where there is a space and a tab character between the [ and the ]
removes trailing spaces from each line.
How can I combine these two sed commands so that both empty lines and
trailing spaces (and tabs) are removed? Thanks.

hzmonte@hotmail.com wrote:
> From: qazwart
> Date: Thurs, Apr 7 2005 9:20 am
> Email: "qazwart" <qazw...@gmail.com>
> Groups: comp.unix.shell
>
> Remember that sed has more commands in it than just "s" for
> substitution:
>
> sed '/^$/d'
>
> Any line that matches the pattern "/^$/" (blank lines) will be deleted
> from the input. If you want to delete lines that may contain spaces and
> tabs, but nothing else, you need to use this:
>
> sed '/^[ \t]*$/d
>
> The "\t" doesn't work with all versions of sed, so you might need to
> use a real tab character instead.
>
> ============================
> sed '/^$/d' works, i.e. removes empty lines, but sed '/^[ \t]*$/d' does
> not - the lines that have tabs and spaces are still there. I tried
> sed '/^[]*$/d' (a real tab between the square brackets)
> and
> sed '/^*$/d' (a real tab between ^ and *)
> and neither works. (The real tab does not show up in the command
> line.)

you may try "POSIX character class" to see if it s.

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

which removes lines containing only whitespaces(TAB, NEWLINE,
SPACE,.....)

Xicheng

hzmo...@hotmail.com wrote:
> > sed '/^[ \t]*$/d' does not work
> Sorry guys, I just found out that
> 1. I probably missed the space inside the square brackets, and
> 2. I did not know I need to type a Ctrl-v before typing a real tab in
> order for the shell to recognize the tab character
> Now it works.
> Further, sed 's/[ ]*$//'
> where there is a space and a tab character between the [ and the ]
> removes trailing spaces from each line.
> How can I combine these two sed commands so that both empty lines and
> trailing spaces (and tabs) are removed? Thanks.

Just connect them with a simicolon:

sed '/^[ ]*$/d; s/[ ]*$//;'

Xicheng :-)

Xicheng Jia wrote:
> hzmo...@hotmail.com wrote:
>>>sed '/^[ \t]*$/d' does not work
>>Sorry guys, I just found out that
>>1. I probably missed the space inside the square brackets, and
>>2. I did not know I need to type a Ctrl-v before typing a real tab in
>>order for the shell to recognize the tab character
>>Now it works.
>>Further, sed 's/[ ]*$//'
>>where there is a space and a tab character between the [ and the ]
>>removes trailing spaces from each line.
>>How can I combine these two sed commands so that both empty lines and
>>trailing spaces (and tabs) are removed? Thanks.
>
> Just connect them with a simicolon:
^^^^^^^^^
An ape's digestive tract? That must be messy.


John
--
use Perl;
program
fulfillment