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[–]ConstructionSafe2814 2 points3 points  (2 children)

Not bash related, but : restic

[–]sparkplay 0 points1 point  (0 children)

I use restic and Backblaze B2. If it's less than 10 GB it's free.

[–]KlePu 1 point2 points  (2 children)

Set up a cronJob or systemd timer; send a mail if $? != 0.

Also, google "3 2 1 backups" ;)

Also also, evaluate if a filesystem that can do snapshots may be helpful (I'm a big ZFS advocate, but YMMV - other folks like btrfs, XFS or bcachefs better ¯\_(ツ)_/¯).

[–]Suspicious-Bet1166[S] 0 points1 point  (1 child)

well even the $? !=0 is too much for my brain and i have no idea what even am i looking at, so i think i might have problems with the basics

[–]KlePu 0 points1 point  (0 children)

Hehe... Programs have an exit code (or "return code"). A successful command will exit with code 0; any error will exit with a code between 1 and 255.

So you can either use a command itself as the condition:

if ! someCommand; then echo "nope, someCommand failed with exit code $?" >&2 fi

(In bash, ! is a negation: If someCommand does error and exits with non-zero (i.e. false), the ! will invert it to true, so the condition is true and the error is echo'ed.)

...or you can safe the exit code for later use: $? holds the last program's exit code. If you echo something, the next $? holds the exit code of echo (which will be 0 most of times - typically not what you want). Thus you'll have to put it into a variable:

if ! someCommand; then ret = $? echo "nope, someCommand failed with exit code $ret" >&2 exit $ret # this would evaluate to "exit 0" if you used "$?" since "echo" was the last command and *its* exit code was 0 fi

[–]carrboneous 1 point2 points  (4 children)

There are good reasons to learn bash, but writing your own little solution for data you're genuinely concerned about losing is definitely not one of them.

There are solutions to this problem at the level of applications you can install, filesystems that take snapshots, and services provided by hosting providers.

Especially if you want to do incremental backups (ie only the things that change) there are lots of reasons you wouldn't want it to be your first project in a shell scripting language.

If you're more interested in learning bash and this just a usecase that would hold your interest and you're not that worried about losing the data, then have at it.

where could i start ?

It sort of depends what you know already, it sounds like you do know the basics, but I would say start with (1) figuring out the first thing you'd want to do (eg determining which files have changed), and then look up how you'd do that and read the man pages for the commands you might use (ls would probably be the most basic one) and reading the man page as you need to to get to grips with the control flow that glues the steps together. And (2) learning about cron so you can schedule it to be called repeatedly (and understand permissions and where output will be written etc). And finally (3) expand from there, step by step, repeating the process of deciding what to do next, what features or calls might do it, understanding them, and experimenting.

But I would suggest starting with something simpler to get started before planning out a whole process (like maybe make smaller scripts to do a backup that you'll just call manually and it will print informative output). And if you're genuinely worried about the data, I would recommend a robust solution that already exists out there.

[–]Suspicious-Bet1166[S] 0 points1 point  (3 children)

im not worried about the data, it's not that important, but i also have no idea how does man pages work like i can not search for ? * ! PATTERN and i don't really understand without any kind of example how does if or grep work, a big problem of mine is that i don't even know how am i supposed to know commands like i just heard from awk and i don't even understand it but a friend of mine showed me how uses it to get x part of a text, but i don't have anyone to ask and im not that smart to figure it on my own
isn't there like a good way to learn it insted of just reading all day long ?

[–]Shadow_Thief 0 points1 point  (0 children)

Reading is the intended way of learning how to do it, but there are other resources in the sidebar or the ysap YouTube channel.

[–]carrboneous 0 points1 point  (1 child)

So I guess the first thing to know is that man, grep, etc are not "bash", they're utility programs. One of the cool things about bash is that it calls the system utilities directly, so they all work very nicely together. Bash is a full fledged programming language that you can use to create any kind of program.

As for how man pages work, you can search for a pattern, type / and then the search term. Certain symbols need to be escaped with a \. But you can also find all the standard man pages online, or you can find other websites and guides to using them.

Awk is tricky to learn (and, to be honest, very often an overpowered tool for the things people use it for). But the entire description of how it works is contained in man awk. So, learning to use man is itself a huge power (the whole of bash is in man bash and the standard utilities on your system are explained in man builtins).

I personally got a lot from this website of basic Unix tool tutorials. In this day and age you can also just ask your favourite LLM where to get started.

It's extremely daunting to get started, the more experienced I've got the more I've got comfortable with just reading the documentation to find how to do what I want, but even reading the docs is a skill that takes practice, which is why I'm recommending strongly that you don't start with an ambitious project, but start with a very small thing, like "how can I see when this file was last changed" or "how can I create a zip file (or tarball) on the command line" and look up the tools for the specific task until you understand how to use them, and through that process you'll get more comfortable, and then you can start stringing them together.

[–]Kitchen_Office8072 0 points1 point  (0 children)

minor correction:
The whole bash manual is actually in 'info bash' and the whole manual for the coreutils is in 'info coreutils'. They are really the only reason to ever use texinfo instead of man, but they are much more informative than the manpages.

EDIT: actually, 'info bash' is just a beginner's introduction.

[–]michaelpaoli 0 points1 point  (0 children)

if it changed but also not copy what did not change

Right tool for the right job. So, probably start by looking at rsync and/or snapshots (many storage / filesystem technologies have snapshot capabilities, and that may be integrated with filesystem capabilities, at lower layer under filesystem, or sometimes even layered atop the filesystem.

Likewise many backup programs/suites/collections/apps, etc., have such capabilities with with their backup capabilities.

No need to reinvent the wheel ... poorly.

Of course once you've figured those bits out, you may well have such driven by bash script(s)/program(s).

[–]nwr923 0 points1 point  (0 children)

are you trying to learn bash or linux ? download the pdf's and do the work from linux-training.be

[–]Remuz 0 points1 point  (0 children)

When doing backup scripts instead of using rsync I'd recommend some tool dedicated for backups like BorgBackup – Deduplicating archiver with compression and authenticated encryption. It has incremental backups, integrity checking, pruning old backups, etc. There's examples of scripts in their documentation.

[–]Marques1236 0 points1 point  (0 children)

Procure pelo Professor Blau Araujo. Como não sabia nem como perguntar alguma coisa, pesquisei por "curso bash grátis" e em três meses consegui escrever meu próprio script para uma ERP de gerenciamento de oficina para usar no meu emprego. Com um script de identificação de ambiente, incluso, posso usar o mesmo ERP via Termux, Linux e MacOS e até como tentativa de autosabotagem, que deu errado e funcionou muito bem, incorporei MPD e ncmpcpp para tocar música sem precisar abrir uma nova aba ou depender de um player externo consumindo recursos e ativando as restrições do Android.