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Emptying files in a loop

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# 1  
Old 06-14-2010
Emptying files in a loop
I'm trying to write a script that will empty all contents in a set of files in a directory - without deleting the files themselves.
I know the command (at BASH prompt) is: > (filename)

I'm iterating over all files in the directory and calling the > command thus :

Code:
FILES=*.log
for f in "$FILES"
do
        echo "Emptying file "$f
        > $f
        echo "Emptied file "$f
done

However, this doesn't seem to be doing anything - what am I missing?

Jim
# 2  
Old 06-14-2010
It should work:
Code:
civ:/datanfs/data $ echo $F;ll $F;>$F;ll $F
ls_out.txt
-rwxr-x---   1 vbe        bin           1039 Jun 14 17:48 ls_out.txt
-rwxr-x---   1 vbe        bin              0 Jun 14 17:49 ls_out.txt



---------- Post updated at 17:56 ---------- Previous update was at 17:52 ----------

Second thought: Its maybe your script - but a guess since I use ksh and have no bash to test... I suspect the FILES=*...
It should be:
Code:
FILES=$(ls *.log)

Or its equivalent for bash...
# 3  
Old 06-14-2010
Changed it to

Code:
FILES=$(ls *.log)
for f in $FILES
do
        >"The file : $f"
done

It throws
syntax error at line 1: `FILES=$' unexpected

this is odd since
FILES=$(ls *.log) works at the bash prompt
but not inside a .sh file!!!! Any idea why this could be happening?
Last edited by SixSigma1978; 06-14-2010 at 01:19 PM..
# 4  
Old 06-14-2010
AS I said Im no bash specialist... but I would try:
Code:
export FILES="$(ls *.log)"
...

# 5  
Old 06-14-2010
Quote:
Originally Posted by SixSigma1978
Code:
FILES=$(ls *.log)
for f in $FILES

How about ...

Code:
for FILE in $( ls *.log )

This works in Bash. (Not sure about the sh shell you're mentioning, though ...)
Last edited by dr.house; 06-14-2010 at 01:33 PM.. Reason: remark added
# 6  
Old 06-14-2010
Quote:
Originally Posted by SixSigma1978
Code:
FILES=*.log
for f in "$FILES"
do
        echo "Emptying file "$f
        > $f
        echo "Emptied file "$f
done

However, this doesn't seem to be doing anything - what am I missing?

Jim
That code is fine, just don't quote "$FILES". The double quotes prevent file globbing from occuring, so "$FILES" expands to "*.log" and that's it. The loop will execute once and try to truncate a file named *.log. Without the quotes, $FILES expands to *.log which is then expanded further into a list of all files that match the pattern.

Regards,
Alister
This User Gave Thanks to alister For This Post:
SixSigma1978
# 7  
Old 06-14-2010
Quote:
Originally Posted by alister
That code is fine, just don't quote "$FILES". The double quotes prevent file globbing from occuring, so "$FILES" expands to "*.log" and that's it. The loop will execute once and try to truncate a file named *.log. Without the quotes, $FILES expands to *.log which is then expanded further into a list of all files that match the pattern.

Regards,
Alister
Alister - that did it. Tho am pretty sure everyone was pretty much right in the end as well!! Sucks to be newb!!! Smilie

Thanks all!!!
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