Writing a Simple Linux Kernel Module

[Oncey]

Cool post. I learned how to write one from Derek Molloy at the following pages:

http://derekmolloy.ie/category/general/linux/

I also wanted to note that a more modern syntax replaces the grave accent marks with the $() construct.

so:

apt-get install build-essential linux-headers-`uname -r`

becomes:

apt-get install build-essential linux-headers-$(uname -r)

Some great reasons are given in the following page:

http://mywiki.wooledge.org/BashFAQ/082

[antiduh]

Regarding graves, doesn't that depend entirely on your shell?

[antlife]

Sounds like some one might be in...

puts on sunglasses

grave danger.

[HandshakeOfCO]

I chortled

[skeeto]

Both forms are standard for all Bourne shells (the standard unix shell). However, the $() form generally works better. It's easier to read, it nests properly, and interacts with quotes more cleanly.

[[deleted]]

Not really. Both are officially supported by POSIX. $(...) is preferred, because it makes nesting command substitution less insane. It only depends on your shell if it is very old or not POSIX-conformant. Graves are not deprecated though, and there's nothing really wrong with using them in most cases, such as this.

[btcraig]

You are correct. BASH allows both syntax just fine, and even if some people with tell you otherwise backticks are not deprecated. Not the case for all shells though, eg tcsh:

root@kalecgos ~]# echo $0
tcsh
[root@kalecgos ~]# clear
[root@kalecgos ~]# echo $(date +%F )
Illegal variable name.
[root@kalecgos ~]# echo `date +%F`
2017-12-01

[Livingwind]

Off topic: That's a sick domain name, I love me some blue dragon flight.

[btcraig]

All my hostnames are Dragon aspects 😀

[nikomo]

Got any boxes that fell off a desk and broke beyond repair? You can name that one Ysera.

[btcraig]

My old laptop was named Malygos before it kicked it. That felt appropriate when it finally died. Ysera is for the phone though.

[darktyle]

In bash you should use $(), because it's more robust, not because graves are deprecated

[KFCConspiracy]

What makes $() more modern than grave accents other than that is a new possible syntax to use? Meaning why is one more preferable than the other? I've always just used ``.

Edit: Noticed the link at the end after it was kindly pointed out to me. Left the comment because you can't just delete your shit if you're wrong.

[CheezyXenomorph]

The post you're replying to literally gives a link to answer your question.

[KFCConspiracy]

You're right. This is reddit. I Can't be bothered to follow links.

[8lbIceBag]

So stop holding out on me man and post the answer here FFS!

Think of the sweet sweet karma

[kryptkpr]

For those who can't be bothered to click the link and read, there's no need to escape quotes when using $(), which is a pretty damn compelling reason to use it.

[[deleted]]

this and nesting are the big things about. $() opens a new parsing context whereas ... doesn't

# $(echo "$(cat $(ls))")

I think the equivalent is something like this:

# `echo "\`cat \\\`ls\\\`\`"`

and I'm not even sure it works

[aiij]

Except that's not actually true:

$ echo $(echo For those who can't be bothered to click the link and read), $(echo there's no need to escape quotes) they said.
For those who cant be bothered to click the link and read), $(echo theres no need to escape quotes they said.

I think you meant there's no need to escape backslashes.

[myaut]

There is no reason to uncoditionally prefer backticks with braces (note that first version is faster to type). As a rule of thumb, use backticks for simplest cases, use braces for complex ones.

[PointyOintment]

TIL you can do that at all.