I can't figure out the error message.

Uncle_Theodore · 12-31-2007, 03:07 AM

In the original script "if" was commented out, but the corresponding "then" was not. That's why bash said "unexpected token 'then'"...

Why did you spend so much time correcting a commented out line?

dive · 12-31-2007, 03:08 AM

Quote:

Originally Posted by gnashley

Code:

if [-e "$to" ] ; then

Might wanna edit that and add a space

gnashley · 12-31-2007, 05:28 AM

Thanks dive, I should have schecked that $%&"!)? code before posting -makes me look as lazy as the OP...

Gins · 12-31-2007, 02:28 PM

Now it works.
Thanks for all the help.

if [ "$#" -ne 2 ]

Here ne means 'not equals'.
What is the reason for giving the value 2 here?
Can't we write 3, 4, 15 some other higher value?

I replaced 2 with 32. The program didn't work. I mean copying of one file to another file did not take place. However, there was not any error message; why is that?

Nylex · 12-31-2007, 02:34 PM

$# presumably gives the number of arguments to the script. So, it makes sense to test that $# is not equal to two, because your script requires two arguments: the source and destination files. If you've supplied fewer or more arguments, that doesn't make sense for copying.

Gins · 12-31-2007, 02:46 PM

Thank Nylex

if [ -e "$to" ] ;

I guess '' e '' means the existence. It just checks whether a file named 'to' is on my system.
Am I correct?

What would be the position if the destination file is write protected?

Uncle_Theodore · 12-31-2007, 02:49 PM

Yes, it checks whether the file, whose name stored in the variable "to", exists.

Gins · 12-31-2007, 03:08 PM

Thanks Uncle_Theodore

If the file named 'to' is write protected, will it overwrite?

Tinkster · 12-31-2007, 04:29 PM

Quote:

Originally Posted by Gins

Thank Nylex

if [ -e "$to" ] ;

I guess '' e '' means the existence. It just checks whether a file named 'to' is on my system.
Am I correct?

What would be the position if the destination file is write protected?

man bash
man cp

Cheers,
Tink

Gins · 12-31-2007, 05:44 PM

No, I didn't find any relevant information in the man pages of 'bash' and 'cp'.

Uncle_Theodore · 12-31-2007, 05:49 PM

Quote:

Originally Posted by Gins

Thanks Uncle_Theodore

If the file named 'to' is write protected, will it overwrite?

If the user, under whose name your script runs, does not have write permissions on the destination file, it will not be overwritten.

Tinkster · 12-31-2007, 06:52 PM

Quote:

Originally Posted by Gins

No, I didn't find any relevant information in the man pages of 'bash' and 'cp'.

How long did you try for? 1 second, 3 seconds?

man bash
/-e
n
(n x 5 on my machine, took me 4 seconds to get there)
gives you EXACTLY the answer to the -e question of yours.

I think you're just a lazy person who expects others to
regurgitate knowledge and spoon-feed it to you.

I have a splendid idea: why don't you re-write all the
man-pages you don't like reading in a nice way that fits
your taste, and start giving back to the community that
has been pampering you for years in that way?

Cheers,
Tink

gnashley · 01-01-2008, 02:31 AM

YOu can get a quicker idea of wht the -e and other such oprions mean by reading the ma page for 'test'. These:

Code:

[ -e file ]
[ -x file ]
[ -r file ]

and other such constructs are constructs of the test program. The '[' means 'test'. However, these are are handled internally by the bash builtins so there are a few differences(bash can handle double brackets, etc). But, still, for the basic usage and tests you may find it much easier to read the 'test' man page rather than the bash man page, which is very long.

Gins · 01-01-2008, 05:55 AM

Gnashley
Yes, the command 'man test' gave me the following:

-e FILE [ This means FILE exists]

-f FILE [This means FILE exists and is a regular file]

-x FILE [ This means FILE exists and execute (or search) permission is
granted]

I have file called 'w3' on my system. It is a text file.
I tested the command 'test'. I didn't write a shell script program.

Ni@linux-3vxw:~> test [ -e w3 ]
bash: test: too many arguments
Ni@linux-3vxw:~> test [ w3 ]
bash: test: w3: binary operator expected
Ni@linux-3vxw:~>
Why did I get a strange output?
----------------------------------------------------------
I can't understand what Tinkster has written.

gnashley · 01-01-2008, 09:10 AM

Here's an example of usage with test instead of brackets:

Code:

#!/bin/sh
# copy a file
if test $# -ne 2 ; then
  echo "Usage: mycp from to"
  exit1
fi

You could also write the same thing like this:

Code:

test $# -ne 2 && echo "Usage: mycp from to" && exit 1

You asked about checking to see if a file is non-writeable:
if ! [ -w file ] ; then