Shell Programming and Scripting

Could somebody please provide me with verbatim description / purpose of the following ?

Code:

set dummy $ac_prog; ac_word=$2
set dummy $ac_tool_prefix; ac_word=$2

could it be written

Code:

set dummy $ac_prog; 
ac_word=$2
set dummy $ac_tool_prefix; 
ac_word=$2

.....more code here

Code:

set dummy ${ac_tool_prefix}strip; ac_word=$2

Thanks , appreciate you taking time to help me.

What you posted is not bash syntax. Some other shells use set somewhat like what you wrote. Where and what is your source for this code?

PS:
1. please use code tags
2. please give us the name of your UNIX-- like ubuntu, HP-Ux

check out: echo $SHELL

Thanks for reply.

Do you want me to post the entire "configure" ? It's about 15000 lines.

How is that going to answer my question ?

I am looking for a description of "set" as used.

set sets positional parameters

Code:

set hallo anne
echo $1
-> hallo
echo $2
-> anne

For a description read ...

Code:

man $SHELL

To help better, please specify your environment as already requested, so the people here can help better. Different Environments behave differently.

Written as is, the first command will set the positional parameters to the string constant "dummy" and the value of $ac_prog. Check it with e.g. echo $@. Then, ac_word will be assigned the second pos. parameter's value, i.e. the value found in $ac_prog.


Yes, commands in bash can be written each on its own line.


The last command will set the second pos.param. to a string concatenated from ${ac_tool_prefix}'s value and the string constant "strip".

It does ac_word=(first word of $ac_prog) and just uses dummy as insulation:

Code:

set dummy a b c d e # $1=dummy, $2=a, $3=b, $4=c etc
word=$2

This looks pointless but is actually in case $ac_prog contains contents set would throw up on, like -x argument argument which set would take as weird commandline arguments and crash with syntax errors, or worse, set shell configuration parameters which change how the program works.

set -- arguments is the modern way, but ./configure is backwards-compatible with 1977 in case it has to run on someone's PDP.

./configure is machine-generated so often looks a little pointless or sketchy.