How to clear contents of a file without deleting it.


 
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# 1  
Old 08-07-2012
How to clear contents of a file without deleting it.

Hi,

I have a script which will use an input.txt file as an input file.
I am providing data to this input file in the script and once the script is executed, I want to clear all the contents of this file as during the second time use of this script, I'll be appending the data in this input file.

So basically I want to know a way using which I can just clear all the contents of the file input.txt and make it a blank file. Like one which is just created with no data in it.
Can this be done.

Thanks in advance!
# 2  
Old 08-07-2012
Code:
# first use of script, clears file
./script > filename
# second use of script, appends file
./script >> filename

# 3  
Old 08-07-2012
Code:
> filename
or
cat /dev/null > filename
echo "" > filename

# 4  
Old 08-07-2012
Quote:
Originally Posted by itkamaraj
Code:
> filename
or
cat /dev/null > filename
echo "" > filename

'echo' creates a file with one blank line in it. Not empty.

You don't need cat or /dev/null here.
Code:
: > filename

# 5  
Old 08-07-2012
Thank's a Ton guys. It really helped me.
Specially to Corona688... that solution is awesome!!!!

UNIX is amazing and equally amazing are all you guys :-)
# 6  
Old 08-07-2012
This works fine, no need use even nop = : command.
Code:
> filename

This method is correct method to clear open log files. Not rm.
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