Bash Command to Remove Spaces

CincinnatiKid · 09-14-2010, 09:41 AM

*I meant to post this in Linux General, can one of the moderators move it?*

I am reading the output of /proc/acpi/thermal_zone/ATF0/temperature in a program to read my CPU temp. I am using cat like the following:

Code:

#cat /proc/acpi/thermal_zone/ATF0/temperature
temperature:                       49 C

I basically want to get rid of the spaces in between temperature and the actual temperature. Is there a command I can pipe the cat output to, to remove the spaces. I have seen suggestions for sed, or tr, but for some reason I cannot get them to work properly.

druuna · 09-14-2010, 09:44 AM

Hi,

The following removes all spaces:
sed 's/ [ ]*//' /proc/acpi/thermal_zone/ATF0/temperature

If you want to leave one space:
sed 's/ [ ]*/ /' /proc/acpi/thermal_zone/ATF0/temperature

Hope this helps.

kurumi · 09-14-2010, 09:56 AM

Code:

ruby -ne  'gsub(/  +/,"");print $_' /proc/acpi/thermal_zone/ATF0/temperature

CincinnatiKid · 09-14-2010, 09:59 AM

I used the sed method and it worked great. Thanks.

druuna · 09-14-2010, 10:03 AM

You're welcome

H_TeXMeX_H · 09-14-2010, 10:57 AM

Here's what I would use:

Code:

cat /proc/acpi/thermal_zone/ATF0/temperature | tr -d [:space:]

That sed command cannot handle anything but spaces, so it won't handle tabs or newlines (if they are in there). If there are none then it will work ok.

druuna · 09-14-2010, 11:17 AM

Hi,

The OP talked about spaces and a specific scenario......

Here's one that does all white space and multiple instances on a line:

sed 's/[[:space:]][[:space:]]*/ /g' infile

Always better to use one command instead of two and a pipe

H_TeXMeX_H · 09-14-2010, 11:39 AM

that works, and there could have been a tab in there, how could you know ?

gnashley · 09-14-2010, 01:16 PM

You said bash right? forget tr, sed & Co.

Code:

while read line ; do
	echo $line
done < /proc/acpi/thermal_zone/ATF0/temperature

druuna · 09-14-2010, 01:38 PM

@gnashley:

Nylex · 09-18-2010, 05:56 AM

Quote:

Originally Posted by lewisforlife

*I meant to post this in Linux General, can one of the moderators move it?*

In future, please use the "Report" button (bottom right of the post) to ask the moderators to move threads. Doing so is guaranteed to get their attention (I believe an email is sent when posts are reported), but posting in your thread is not, because they aren't necessarily going to read it (whatever the reason may be - they can't look at every single thread, for example).

Having said that, I've reported it for you now. It's probably better off in Programming, but obviously the mods will make that decision.

MTK358 · 09-18-2010, 08:03 AM

Quote:

Originally Posted by druuna

Hi,

The following removes all spaces:
sed 's/ [ ]*//' /proc/acpi/thermal_zone/ATF0/temperature

If you want to leave one space:
sed 's/ [ ]*/ /' /proc/acpi/thermal_zone/ATF0/temperature

Hope this helps.

What's the reason for the square brackets if there's one character inside? Just a space would work the same.

Also, why look for a space followed by 0 or more spaces, when you can use the + operator which means one or more?

druuna · 09-18-2010, 08:43 AM

@MTK358:

Quote:

What's the reason for the square brackets if there's one character inside?

Habit, I automatically use space and tab when hunting for whitespace (I should use :space: more often) and forget that the square brackets aren't really needed when removing either of the two. I don't use the + that much because in some programs it needs to be escaped (sed being an example).

This would indeed work:

Code:

sed 's/  */ /' /proc/acpi/thermal_zone/ATF0/temperature

This would not:

Code:

sed 's/ */ /' /proc/acpi/thermal_zone/ATF0/temperature

But this would:

Code:

sed 's/ \+/ /' /proc/acpi/thermal_zone/ATF0/temperature

kurumi · 09-18-2010, 08:53 AM

Quote:

Originally Posted by druuna

I don't use the + that much because in some programs it needs to be escaped[INDENT](sed being an example).

sed -r ?

druuna · 09-18-2010, 08:58 AM

Quote:

Originally Posted by kurumi

sed -r ?

Yes, that would also work in sed's case. Like I stated already: Habit.