[CLUG] Shell script newbie

[Peter Flynn]

Jean-Pierre Thibert wrote:
> Hi everybody and happy new year,
> 
> I'm learning shell script and have some questions. Could you help me?

The best book I have read on this is "Classic Shell Scripting" by Arnold 
Robbins and Nelson Beebe. Strongly recommended (I forgot to say this 
when we were talking in the pub before Christmas).

> 1)I have a variable with a value between 00.00 to 100.00 (ie : 12.58)
> I want to extract the integer. Something like X=int(MYVAR)

Bash doesn't support floating-point math _per se_, so it will think of 
this as a string. See man bash and read about arithmetic evaluation and 
arithmetic expansion.

> How to do that? I didn't find out after a lot of research.

Here's another (dirty) solution:
   X=`echo $MYVAR | awk -F. '{print $1}'`
There are others, eg
   X=`echo $MYVAR | sed -e "s+\..*$++"`

> 2) I think wget command has an output only as a file not a variable.
> Am I right?

The man page says:

  -O file
  --output-document=file
  The documents will not be written to the appropriate files, but all
  will be concatenated together and written to file.  If - is used as
  file, documents will be printed to standard output, disabling link
  conversion.  (Use ./- to print to a file literally named -.)

but I find this does not work: wget -O - http://www.google.ie saves the 
output in a file called "-".

To pipe a URI into further commands, use dog (a replacement for cat, ha 
ha)...if it's not installed, sudo apt-get install dog should do it. Then 
you can type

dog --no-header http://www.google.ie | more stuff

> 3) I tried to find a script commands reference on Internet and a 
> detailed training unsuccessfully.
> Have you some good links?

That book is the best place to start.

///Peter