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Old 04-20-2009, 05:57 PM   #1
v333k
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check if directory exists using shell script


hi everyone,
I am trying to write some small script file that will check if a USB stick is connected to my pc or not. I can't seem to get it to work, but I am sure it is a very simple fix.

here is what I have in my file:
Code:
#!/bin/bash

usb_path = "/media/disk/"

if[ -f $usb_path ]
then
    echo "path exists"
else
    echo "path does not exist"
fi
I named my file as: check_usb.sh
and I changed permissions: chmod 755 check_usb.sh

The error I keep getting is this:
# ./check_usb
./check_usb.sh: line 3: usb_path: command not found
path exists

I am running on Fedora core 10.
Can anyone help me figure out what the problem is?

If I run these lines through console it works fine (meaning, I type the commands in this file straight in the command line/console).

thanks in advance.
 
Old 04-20-2009, 06:13 PM   #2
GazL
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It's the spaces around '='. Try

Code:
usb_path="/media/disk/"
also, you should have a space between your if and the '['.

Last edited by GazL; 04-20-2009 at 06:16 PM.
 
Old 04-20-2009, 06:14 PM   #3
Robhogg
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Two small problems. Linux shell-scripts are very fussy about spacing in certain places:
Code:
usb_path = "/media/disk/"
There must not be any spaces around the assignment operator (=)
Code:
if[ -f $usb_path ]
There must be spaces around the square brackets.

This is really for the same reasons. A command is separated from its arguments by (a) space(s), so usb_path is seen as a command and not an assignment, while the [ ... ] construction is actually a command (it's equivalent to test ...) so needs the spaces.

Hope this helps,
Rob
 
Old 04-20-2009, 06:25 PM   #4
v333k
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PERFECT!

Thanks a lot!!!!
 
Old 04-20-2009, 07:27 PM   #5
Robhogg
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Another thought just occurred - if you're wanting to check that $usb_path exists, and it is a directory, you'd need:
Code:
if [ -d $usb_path ]
... as -f tests if something is a normal file (i.e. not a directory, block device, etc). If you just want to test that it exists (and don't care what sort of file it is), you could use:
Code:
if [ -e $usb_path ]
 
Old 04-21-2009, 09:59 AM   #6
v333k
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GREAT! Thanks for the tips!
At the moment, I want to check if the usb is connected to my PC - and I don't really care about other parts; therefore, it looks like using -e will be my best choice.

Thanks again!

Quote:
Originally Posted by Robhogg View Post
Another thought just occurred - if you're wanting to check that $usb_path exists, and it is a directory, you'd need:
Code:
if [ -d $usb_path ]
... as -f tests if something is a normal file (i.e. not a directory, block device, etc). If you just want to test that it exists (and don't care what sort of file it is), you could use:
Code:
if [ -e $usb_path ]
 
Old 04-23-2009, 06:31 AM   #7
jisjis
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Quote:
Originally Posted by GazL View Post
It's the spaces around '='. Try

Code:
usb_path="/media/disk/"
also, you should have a space between your if and the '['.

Linux is so finicky !!!


Linux

Last edited by jisjis; 04-26-2009 at 04:43 AM.
 
Old 04-23-2009, 07:21 AM   #8
H_TeXMeX_H
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Quote:
Originally Posted by jisjis View Post
Linux is so finicky !!!
Ever tried C programming ?
 
Old 04-23-2009, 09:09 AM   #9
v333k
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Yes - actually, I am writing my socket server in C, but there are certain things that I would like to run in shell from a C program.
For example, it will be much faster (in my opinion) to obtain the directory list by running a shell script (ls -la) instead of writing a C function that will try to parse the directory, etc... etc... etc....

It is also nice to try something new and not go back to known methods of implementation!

Just a clarification - that wasn't me who said Linux is finiky!

In any case... thanks for your suggestion!
 
Old 04-23-2009, 09:29 AM   #10
Libu
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Quote:
Originally Posted by jisjis View Post
Linux is so finicky !!!
Well its not linux, its bash and you can use perl if you want to !
 
  


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