[Nottingham] Bash: test "file exists" - gotme again

david wolfson eaxdrw at nottingham.ac.uk
Thu Oct 14 14:23:23 BST 2004

I'm back in bash land, with another gotme, this time of my own making.

It's a similar setup, where I want to batch process a lot of files. I 
thought I'd set up a while loop, to keep running as long as a file of 
the given file name exists, but it always goes 'a file too far' (i.e. if 
my last file is file_119.tif and it tries to run file_120.tif).

There's some other gumph in the loop (sorting out zero padding and the 
like), but the basic structure is as follows

while [[ -a "$filename" ]]; do
            echo "processing file: "$filename
            file_no=$(($file_no + 1))  

I've tried several other forms such as;

until [ ! -z $filename ]; do

but with the same outcome; always one file too many.  At the moment this 
is an annoyance, but it'll soon become a real pain.

If anyone can spot my blooper, or point me in the direction of some 
advice (I got this far from the evaluation section of the man pages) I'd 
be grateful.



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