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Gentoo users be like (sh.itjust.works)
submitted 5 months ago by 0x4E4F@sh.itjust.works to c/linuxmemes@lemmy.world
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[-] MajorHavoc@programming.dev 38 points 5 months ago* (last edited 5 months ago)

I believe the left hand is a shell fork-bomb, on the assumption that anything that zany is probably malicious.

And the right hand is a way to tell Make to use up all available system resources:

"-j [jobs]’ ¶
‘--jobs[=jobs]’
Specifies the number of recipes (jobs) to run simultaneously. With no argument, make runs as many recipes simultaneously as possible. If there is more than one ‘-j’ option, the last one is effective. See Parallel Execution, for more information on how recipes are run. Note that this option is ignored on MS-DOS."

Edit: I think the make command is technically only a problem when run for a Makefile that tries to do too many things, and has at least one mistake in dependency controls. So... for every Makefile I ever encountered (or that I ever wrote!)

Yeah. They're the same picture

[-] Voroxpete@sh.itjust.works 25 points 5 months ago* (last edited 5 months ago)

You are correct, left hand is a fork bomb. Specifically, it creates and then runs a function named ":". What this function does is pipe its output into itself while running in a background process, which instantly spawns infinite copies of itself. Technically I believe the : character could be any character as its just a name. The creator just picked a colon for aesthetics.

[-] laurelraven@lemmy.blahaj.zone 13 points 5 months ago

I always just kind of glazed over looking at that and just know "it's a fork bomb" and basically what it does

With your explanation, I can now actually understand all the parts and how they work, it actually makes sense

[-] Mixel@feddit.de 5 points 5 months ago

Now I get why it does what it does and how it works. I never thought that the colon was the variable name but it makes so much sense!

[-] Max_P@lemmy.max-p.me 6 points 5 months ago

I think it can also get weird when you call other makefiles, like if you go make -j64 at the top level and that thing goes on to call make on subprojects, that can be a looooot of threads of that -j gets passed down. So even on that 64 core machine, now you have possibly 4096 jobs going, and it surfaces bugs that might not have been a problem when we had 2-4 cores (oh no, make is running 16 jobs at once, the horror).

[-] AVincentInSpace@pawb.social 4 points 5 months ago

so without an argument to -j the number of concurrent jobs is unbounded???

this post was submitted on 19 May 2024
239 points (96.9% liked)

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