shell script : appending directory path and filename

Question

I want to copy a file from a directory using shell script

Suppose I save the directory and file name seperately as

dir=/home/user/directory/
file=file_1

to copy the file Im using this command in my script

cp $dir$file .

But I get this error

/bin/cp omitting directory '/home/user/directory'

I have tried all combination eg. omitted the trail backslah from variable dir, etc but nothings working. I cant understand what is wrong with this code. Pleas help

Maybe the command $dir$file is not getting unpacked in the shell (ie only the directory variable is getting unpacked, not the file variable)!!!!!

Answer 1

It looks like you are having problem with expansion in cp $dir$file . In order to prevent possible problems, it is better to protect your variable with braces and double quote the full path/file to make sure you don't get caught by spaces in either the filename or heaven forbid the user's dirname:

cp "${dir}${file}" .

This will prevent the possibility the second $ is missed. Also make sure you have read access to other users /home (if you are root or using sudo you should be fine)

Answer 2

If you see this, when you somehow assign an empty string to file somewhere. Search your script for file= and unset file .

You can also debug this by adding

echo ".${file}."

in the line before the cp command. I'm pretty sure it prints .. , ie the variable is empty or doesn't exist.