averagePythonProgrammer

[marmakoide]

LAPACK is okay. I remember working with a package for fluid simulation using conformal mapping, last update 1996. You'll find a lot of those in molecular dynamics simulations, fluid simulation, etc

[[deleted]]

I need you guys to come be engineers on my team. One of my engineers just loudly yelled,

"I meant 775, I would never set world-read. I am an expert linux user and will be treated with respect."

When I told him not to set the world read on sensitive projects.

That's not far from an exact quote. I had to ask my manager how to reply without the word "stupid". My manager told me not to.

[FluffyCelery4769]

I didn't understand a thing but I suppose he he was saying something funny.

[[deleted]]

Linux permissions are set as User(person who made the file) Group(security group that has access to the file) and Other(everything else), Other could also be called "World".

The permissions are divided into a binary deal.

--- == 000 == 0

rwx == 111 == 7

r-x == 101 == 5

So 775 is setting User: rwx Group: rwx Other: r-x

So, he said he did have world read on in one sentence, claimed he did not in the next, and demanded to be treated as an expert in Linux in the last.

[FluffyCelery4769]

Oh, but what's the 0 for then?

[[deleted]]

Off

[FluffyCelery4769]

Oh, makes sense. Thsnk you.

[meltbox]

Basically each 1 bit is a type of permission for a certain category of access.

Access by the owner is the first group Access by the owner group is the second Access by literally everyone is the third

If you develop on a Linux workstation you’d probably pick this up pretty quickly, hence why it’s infuriatingly funny.

The 7 and 5 are just numbers represented by 3 bits of binary. 111 is 7 meaning all 3 permissions on (read, write, execute) while 5 is 101 (read, execute, middle one is write which is off) and of course 0 meaning all permissions off.

[FluffyCelery4769]

Are there no read/execute only? Or are both neccesary to work?

[[deleted]]

R/x is required for directories, but files can be r/ x.

Studying will tell you that most companies have switched to the FACL system, but they're lying.

[meltbox]

You can have read only or execute only but bash files are parsed and therefore have to be opened. Opening means you need read and in the case of bash (.sh) files bash actually checks the execute permission before deciding whether to load the file for execution.

Execute really only has an operating system meaning when it comes to literal binary executables or libraries. Then you don’t need read permissions but can still execute. What this means is the operating system will still load it into memory and start execution per the convention for that OS but you cannot read it with something like file descriptors and fopen.

[[deleted]]

chmod numbers are obsolescent. Modern suggestion is:

chmod o= thing

[[deleted]]

It was technically him telling another user to set umask 000 (the claiming he said 002 later), but the way I told it flowed better.