First of all, Rob, thank you for a fantastic presentation. I was
looking forward to this and did not want to miss this for the world.
People like you remind me of why I got involved in Linux in the first
place. I guess the camaraderie of working on a Commodore never left me,
except Linux is robust and continues to grow. The fact is, BASH is one
of the great reasons to have a Linux System. Of course you have people
with Linux for reasons that are just the consequence of the control that
is afforded to the user: the ability to avoid viruses, the solid
stability of the OS, the customization, the loads of available open
source software. However, the greatest asset of the Linux system is in
the command line. The command line affords the user the flexibility,
where with enough know how, the computer is turned into the tool that it
was meant to be, an indispensable ally for our day to day activities.
Rob, your presentation once again has demonstrated to me the
possibilities that the command line affords, and another reason why I
have chosen to dedicate my self to this system. Also, great audience.
Bill, Kyle, Rafael, everyone, I thought, provided great insight, and
once again, made me glad to be part of this group.
In the next presentation, I would like to propose further exploration of
command line scripting, perhaps going over some of those cron examples
that were not mentioned. I am currently reading a book that was lent to
me by my professor, Linux Kernel Development. I would like to learn more
about kernel development, perl scripting, c scripts, and perhaps even
see a presentation in the future about gaming.
Anyways, once again Rob, thank you. And I am downloading your
presentation now... using Open Office Impress!! ;P
On Wed, 2010-10-20 at 14:34 -0400, William L. Thomson Jr. wrote:
> On Wed, 2010-10-20 at 13:05 -0400, robert mckennon wrote:
> > Feedback??? (Other than it was done on a winblows laptop)
>
> It was a great presentation, and I really appreciate you stepping up
> last minute! Sorry to nit pick on a few things, nothing personal, wasn't
> trying to heckle. Just better to build good habits rather than bad.
> Which is something I am still working on myself, thus pointing it out ;)
>
> Here are some references and info on my nit picking from last night
>
> Both $var and ${var} are valid for variable declaration.
> However ${var} is a better habit for variable declaration.
> http://www.gnu.org/software/bash/manual/bashref.html#Shell-Parameter-Expansion
>
> Also most always it can't hurt to wrap that in double quotes.
>
> "${var}"
>
> That will preserve and respect spaces and special characters. Tends to
> make scripts a bit safer and less error prone.
> http://www.gnu.org/software/bash/manual/bashref.html#Double-Quotes
> http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_03_03.html
> http://www.gentoo.org/doc/en/articles/bash-by-example-p2.xml
>
> At one point this became a major issue in Gentoo. Every ebuild had to be
> updated requiring certain variables to always be quoted, and in general
> all variables in an ebuild. You can't even commit an ebuild via Gentoo's
> repoman (used to commit ebuilds to portage) if variables are not quoted.
> Its become that important.
> http://marc.info/?l=gentoo-dev&m=119105436806707&w=2
> http://dev.gentoo.org/~zmedico/portage/doc/man/repoman.1.html
>
>
> The other point I nit picked on was subshells. While the following is
> both valid for invoking commands, one does it in the same shell, the
> other a subshell.
>
> $(command) or `command`
> http://www.gnu.org/software/bash/manual/bashref.html#Command-Substitution
>
> Pretty sure the later is safer, as the first invokes the command in a
> subshell. However I think they both invoke a subshell.
>
> Subshells involve scope, and fork another process. Which can be a good
> and bad thing, but they need to be understood and used properly. Or you
> can have bugs in scripts that can be cumbersome to debug.
> http://tldp.org/LDP/abs/html/subshells.html
>
> In trying to confirm (which I still have not) if both the above syntax
> fork off a child process in a subshell. I did come across the 100% save
> way to execute a command in a bash script, without forking off another
> process and ended up in a subshell. Using the built in command exec
> http://tldp.org/LDP/abs/html/internal.html#EXECREF
>
> > I have updated the wiki and the presentation is there as well.
> >
> > http://www.jaxlug.org/index.php/2010/10/19
>
> Thanks for adding it to the wiki!
>
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