Store command output into variable

That gets rid of the error "/bin/timeline: line 49: /media/USB: No such file or directory" but the temp variable is still null when I run the script :(

Where are you checking the temp variable? Add an echo before

count=$[$count + 1]

echo $temp

It should be within the loop.

also

count=$[$count + 1]
should be
count=$(($count + 1))

Ok, I can see the temp variable now, but I have defined partition_offsets outside of the loop and if i assign the output to "partition_offsets[$count]=output from command" I still only see partition_offsets holding the correct value while inside the loop and not outside of the loop. What must I do to get the output stored inside of the loop to be visible after I leave the loop? I really need to fill the partition_offsets array inside of the loop for a later use.

It should be available after the loop also unless it is reset somehow. Post the complete script and output from it.

It appears that if you use a loop fed by a piped command the loop will perform within a sub-shell which is why I am seeing this issue.

http://www.nucleardonkey.net/blog/2007/08/variable_scope_in_bash.html
http://nion.modprobe.de/blog/archives/531-Altering-a-variable-outside-the-scope-of-a-loop-influenced-by-a-subshell.html

I have included my modified script. I changed it to make use of the partition_offsets array rather than the temp variable. Below is the output.

[root@SIFTWorkstation /]# timeline /media/USB\ 500GB/Images/6RX99BCP/6RX99BCP.001
-------------------------------------------
/media/USB 500GB/Images/6RX99BCP/6RX99BCP.001p1   *          63   109980989    54990463+   7  HPFS/NTFS
-------------------------------------------
63
count = 0
partition_offsets[0] = 63
-------------------------------------------
/media/USB 500GB/Images/6RX99BCP/6RX99BCP.001p2       109980990   156296384    23157697+   7  HPFS/NTFS
-------------------------------------------
109980990
count = 1
partition_offsets[1] = 109980990
-----outside of loop-----
partition_offsets[0] =
[root@SIFTWorkstation /]#

I have tried changing this to store the fdisk and grep command results to a variable and do a "for line in $lines" style of loop but the loop didn't appear to treat the result of the grep as multiple lines like the current while loop that I am using.

#!/bin/bash
 
#Check that there is one argument passed in
 
if [ $# -ne 1 ]
then
	echo "Usage: $(basename "$0") path"
	echo "  path: path to the image file"	
	exit 1
fi
 
 
 
#Check that the image file exists
 
if [ ! -f "$1" ]
then
	echo "File: "$1" does not exist"
	exit 1
fi
 
 
 
#Grab the basename of the file
 
filename=$(basename "$1")
#echo "Filename: $filename"
 
 
 
#Store the file name without the extension as the case name
 
casenum=`echo $filename | sed "s/\..*//"`
#echo "Case number = $casenum"
 
 
 
#Get the details about the disk image
 
declare -a partition_offsets
count=0
fdisk -ul "$1" 2>/dev/null | grep "6RX99BCP\.001p" | while read line
do
	echo "-------------------------------------------"
	echo "$line"
	echo "-------------------------------------------"
	echo $line | sed "s/.*\.001p[[:digit:]][^[:digit:]]\{0,\}\([[:digit:]]\{1,\}\).*/\1/"
	partition_offsets[$count]=$(echo $line|sed "s/.*\.001p[[:digit:]][^[:digit:]]\{0,\}\([[:digit:]]\{1,\}\).*/\1/")
	#count=$[$count + 1]	
	echo "count = $count"
	echo -n "partition_offsets[$count] = "
	echo "${partition_offsets[$count]}"
	count=$(($count + 1))
done
 
echo "-----outside of loop-----"
echo -n "partition_offsets[0] = "
echo ${partition_offsets[0]}

                                              

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Can you add the following line in the end and see what you get?

echo "partition_offsets = " ${partition_offsets[*]}

I have raised the points to 500 to split between you two.

amit_q: I have tried your suggestion but it still printed out nothing. just "partition_offsets = "

simon3270: the exec command seems to do the trick although I don't fully understand why it works. If you would be kind enough to explain why or at least point me to a good source of information on this subject I would apreciate it.

Thank you both for the assistance!

The "exec" line says that from that point on in the script, standard input comes from the file you specify, not from the keyboard.  Then the "read line" bit, which would normally read from standard input, reads from the file instead.

If your script needed the real standard input later on, there is a way to remember the actual stdin, and reset it after you have read the file (see link below).

I'm not sure where I learnt this - it's just one of the things I have picked up over the years - but I did find a good description on http://www.linuxtopia.org/online_books/advanced_bash_scripting_guide/x13082.html
 
Thanks for the points - made me up to a Qualified Expert!