UNIX for Dummies Questions & Answers

I've a shell script that invokes a URL of an application to do some work, e.g., http://www.abc.com/myservlet?action=helloworld.Does the shell wait for a return value from the URL call before proceeding to the next line of command?

yes, unless you start a new thread and do the operation in the new thread independently. usually you won't be doing this in a shell script

So regardless of what's happening inside the URL call, the next line of command inside the SHELL script would not execute until the URL call ended?

If you are specific to make a call to specific operation and still continue with the next set of lines in the script
it is usually done with an ' & '

Code:

instruction1 &
instruction2 &
instruction3

Actually I want the current line to finish executing before continuing to the next line. So do I still use the '&"?

Unix has a sequential approch in executing the commands unless they are made to run in the background(using & as given in above posts.). ie,

command1
command2
command3

will be executed as command1 followed by command2 followed by command3 irrspective of the outcome of the commands.


If you want to run command2 only if command1 is executed fine and similarly command3 only if command2 is executed, you can do like..

command1 && commmand2 && command3

No you dont have to,

current instruction
next instruction
next + 1 instruction

for the above instruction order, for a sequential flow only if the current instruction is completed executing, control would flow to the next instruction