Shell Programming and Scripting

I'm trying to run following code:

Code:

while [ !(fdisk -l /dev/disk/by-path/*usb* | wc -w) ]
do
echo "Hello World"
done

but I'm getting error on first line:

Code:

./test: line 1: syntax error near unexpected token `('

can anyone please tell me who can i run this loop. Also please tell me what will be syntax of do while loop in case i enter in loop and then check condition at the end. thanks.

can you elaborate more on what you are trying to achieve in the "while" condition

actually I m trying to check if there is any usb connected or not. if usb device is connect then fdisk will give me alot of information so i just decided to see if wc is zero then it will send email saying "No usb" and it will keep checking till usb connected. once usb is connected then fdisk will output something wc is not zero and it will stop sending email or any task that i want to do.

you'd make that correct with

Code:

while [ "$(fdisk -l /dev/disk/by-path/*usb* | wc -w)" -eq 0 ]

but if you just want to see if something with *usb* exists, why run fdisk? the shell globs the path, so you can just check if it expands to existing files. which shell?

if you are planning to send email notifications, add a "sleep" inside your while loop, else your inbox will be swarmed with emails unless you've connect any usb.

actually this is part of a complete program in which i need to shoot an email when a usb is connected and when a usb is disconnected with proper information of usb.

yes df -h shows all drives but i ll have to work more if i use that command (although I'm using it in later part of my program). if you have any other idea you can tell me.

@ 47shailesh Yes definitely I'm using that 2. "sleep"

thanks for reply.

Lose the parentheses and the square brackets:

Code:

while ! cmd1 | cmd2 >/dev/null 2>&1
do
  echo "Hello World"
  sleep 2
done