I'm really new and getting rapidly frustrated...Syntax errors seem to be pretty common.
Here is my code, which is pretty basic
I want to read multiple file names from the console, and check each one to see if it is a valid file name. I've started by trying to write a basic test for one file name, just to see if I can open it. Later I'll get around to reading it, but baby steps first.

while true
do
echo -n Please enter file names to process:
read files
file=`echo ${files} | awk 'BEGIN{FS=" "} {print$1}'`
if [ `filehandle= fopen(${file}, r)` == NULL ]
then
echo Bad file
else
echo Good file
exit 0
fi
done
My file is called File_tester
The error I get is;
File_tester: command substitution: line 18: syntax error near unexpected token `('
File_tester: command substitution: line 18: `filehandle= fopen(${file}, r)'
File_tester: line 18: [: -eq: unary operator expected

I know the problem is with my if test, but what?
Hopefully someone can help
Thanks

Correct me if I'm wrong, but fopen() isn't executable by the shell.

On my FC4 installation:

Also, man -a fopen only yields the man page for the C function.

It looks like you are testing to see if the file is readable; to do this, you would use the bash '-r' test:

Changing the file to:

while true
do
echo -n Please enter file names to process:
read files
file=`echo ${files} | awk 'BEGIN{FS=" "} {print$1}'`
if [ ! -r ${file} ]
then
echo Bad file
else
echo Good file
exit 0
fi
done


did get rid of my syntax error. Thanks However, if I give it an existing file name, it tells me bad file, but if I give it a directory, such as " /etc ", it tells me good file. Obviously, still not working the way I want.
Hopefully you have some more good advice
Thanks

Try giving the full path of the file. eg /etc/fstab not fstab. If you don't give the full path your script will only find files that are in the same directory as the script.

while true
do
echo -n Please enter file names to process:
read files
file=`echo ${files} | awk 'BEGIN{FS=" "} {print$1}'`
if [ ! -r ${file} ]
then
echo Bad file
else
echo Good file
exit 0
fi
done

did get rid of my syntax error. Thanks However, if I give it an existing file name, it tells me bad file, but if I give it a directory, such as " /etc ", it tells me good file. Obviously, still not working the way I want.
Hopefully you have some more good advice
Thanks

That did it. Thanks.

I know this is not part of the original post, but how do I read in multiple args from the shell. In other words, I want to be able to enter x number of file names, then process each one in sequence. I don't know in advance how many will be entered
Thanks

You can use the shift command. It shifts all the arguments down by one. So read $1, do stuff with it, then shift so whatever is in $2 goes into $1, repeat until $1 is empty.

Here's the mechanics behind why that doesn't work:

from man bash
so all you're saying, when you give the -r test a directory is that the directory exists, and is readable. It's not seeing it as a directory. The -d test will test to see if the file is a directory. If you wanted to, you could test to see if the name you are giving is a directory, then if it is, look through its contents file by file.

Take a look at man bash, and search for CONDITIONAL EXPRESSIONS. This will give all of the available file tests. There are dozens. I actually reccomend reading the whole bash man page. (caveat: I've never actually done so myself, but I know that there's a bunch of good stuff in there)