end of file in bash shell
 

Hi,

Could you please tell me how to check the "end of file" by using bash script and c script?

Thanks a lot.
Manojg

For your bash script, how are you processing the file? Tools like cat, grep etc. already know when they're at the end of the file.

Actually, I used:

================
exec 6<file.dat # open the file
read -u 6 dta # read the one line of the file
================

If I loop over the "read -u 6 dta", it will end up at the end of the file. It is fine. But I want to put these quantities in a 1-d array. So, I have give the index for the array. To do this I have to make a loop (over a large number because the program does not know the number of entries in file) and this loop should terminate at the end of the file.
Some thing like this:

======================
declare -a nentry # declare an 1-d array "nentry"
entry=0 # initialize the number of entry
exec 6<file.dat # open the data file

while [ $entry -le 500 ]; do # loop over entries
read -u 6 dta # read one line
nentry[$temp]=$dta # put the quantity in array
entry=$(expr $entry + 1) # increase the index by one
done
======================

The loop will be executed 500 time even if there are only 10 entries. So, I want to terminate the loop after 10th execution of the loop.
One way I can do this is by putting a number (say 22222) at the end of the file and checking for that number by using "if" condition like:

=================
if [$dta -eq 22222 ]; then
break
fi
=================

Then the loop will be:

==================
while [ $entry -le 500 ]; do
read -u 6 dta
if [$dta -eq 22222 ] break
nentry[$temp]=$dta
entry=$(expr $entry + 1)
done
===================

But this does not work because in the data file there are number as well as character. So, the if condition shows problem when it encounters characters.

Manojg,
Like Gilead said, tools like cat handle the end of file for you.
Here is a example of how you can use it in a bash script to do what you describe:

entry=0
for item in $( cat file.dat ); do
entry_set[$entry]=$item
entry=$( expr $entry + 1 )
done

You can see the contents of the array with:

counter=0
while [ $counter -lt $entry ]; do
echo Number stored in array block $counter is ${entry_set[$counter]}
counter=$( expr $counter + 1 )
done

However, if you can, I recommend you use Python instead of a bash script. Although the difference is small in this case, Python can do so much more than a bash script it is often a better tool.
Here is the Python code to write to an "array." I actually used a Python list instead. A list is a kind of variable array.

file_handle = open("file.dat")
entry_set = []
for item in file_handle:
entry_set.append(item)

Viewing the "array" in Python would be:

for i, output in enumerate(entry_set):
print "Number stored in list block", i, "is", output,

I hope this helps

Thanks a lot everybody for your help and information. I will also use Python.
Actually, I was making a dialog box using Xdialog which runs with shell script. Fortuantly, there is Xdialog for Python also.