This will ALWAYS occur if the number of files in the /a/b/c/ directory is very large OR the names of the files or directories are extremely long. As mentioned, the * character is very special. It is *NOT* passed to the ls command at all (under default conditions that is). Instead, the shell replaces the entire string /a/b/c/* with a full listing of all the names in that directory. To see this happen, change your command from:
ls -R /a/b/c/*
to
echo ls -R /a/b/c/*
and you'll see the same error. To see what the ls command sees in a smaller directory, do this:
echo ls /etc/*
Now tell the shell to stop expanding the * by escaping it's special meaning:
echo ls /etc/\*
and:
ls /etc/\*
The \ removes the special meaning of the * character. All this is covered in the manpages: man 5 regexp (the 5 is required, see man man)
So the error has nothing to do with ls but instead is a function of what the shell finds to match. For instance:
cd /a/b/c
ls -R
may work just fine because the expanded expanded list of matching filenames no longer contains the fullpath to this directory. However, add a few thousand more files to this directory and again you'll get the same error. When in doubt, use echo to see what your command line will look like after the shell finishes it's preprocessing.
---------------------------
For extra credit, here's a script that you can use to create 10,000 files to demonstrate the problem:
mkdir /var/tmp/dummy
cd /var/tmp/dummy
typeset -Z20 NUM=10000
while [ $NUM -gt 0 ]
do
touch IamAveryLONGfileNAMEtoSHOWcommandLINElimits_$NUM
let NUM=$NUM-1
done
Then use the * with either echo * or ls *
Warning: This will create a very large directory structure and will take a long time to create and also to remove.
Bill Hassell, sysadmin
