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The Art of Command Line

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Re: The Art of Command Line

#91

Post by unhammer »

binarycrusader wrote: post #6
scrollaway wrote: post #5

> To disable slow i18n routines and use traditional byte-based sort order, use export LC_ALL=C (in fact, consider putting this in your ~/.bashrc). Do not. Having a non-utf8 locale means you won't be able to handle utf-8 sanely ("that's why it's faster") and it will break at the most inexplicable times. Any non-latin1 character appearing in your prompt or command line with this will mess its spacing up for example. Do…

I have to reiterate this; don't do it -- sort order changes and you'll run into other mysterious issues. It's not worth the "performance improvement".

There are good reasons to use LC_ALL=C for certain commands, especially if you want sorting that's stable across different systems. Sometimes you want "aa" to be before "b" even though the Norwegian UTF-8 locale puts it after "å" (which comes after "…zæø"):

    $ echo $'a\naa\nb\nå'| LC_ALL=C sort 
    a
    aa
    b
    å
    $ echo $'a\naa\nb\nå'| LC_ALL=nn_NO.UTF-8 sort 
    a
    b
    å
    aa
Even worse, some characters that are byte-different collate the same:

    $ echo  $'∨\n∧'|LC_ALL=C sort -u
    ∧
    ∨
    $ echo  $'∨\n∧'|sort -u
    ∨
Handling Unicode sanely requires understanding some Unicode.

Re: The Art of Command Line

#92

Post by xorcist »

AYBABTME wrote: post #60
cmrx64 wrote: post #24

> StrictHostKeyChecking=no And welcome to MITM haven. This is awful advice if you care about the first S in SSH.

What would be good is an interactive confirmation when a host fingerprint has changed, instead of a flatout abortion and having to edit your `known_host` file. I have to SSH into hundreds/thousands of VM that reuse the same IPs/FQDN sometimes, and the strict host checking is a major PITA. I haven't turned it off tho, I prefer the pain to MITM.

Don't use SSH in a trust-on-first-use configuration in that situation.

There are two other modes to use. Either DNSSEC with SSHFP fingerprints, or sign your host keys with a CA key that you install on all your machines.

A decent configuration management tool could also keep known_hosts up to date, but it tends not to be worth the trouble. Do the above first.

Re: The Art of Command Line

#93

Post by unhammer »

MarcScott wrote: post #67

I'd never even thought about commenting a line I was half way through writing, when suddenly realising I'd forgotten the correct arguments. I normally end up opening another terminal and using man there.

I do this sometimes when I want to run some command first from earlier in my history, then the commented out command also stays in history so I can continue with it after I've re-run the earlier command first.

Re: The Art of Command Line

#94

Post by unhammer »

Wonnk13 wrote: post #19

pretty good writeup. Learning nohup was a life changing experience for me.

there's also disown. It's a bash builtin, so you'll have to type "help disown" ("man disown" gets you nothing). E.g. to run touchegg and close your terminal, keeping touchegg running:

   touchegg & disown; exit

Re: The Art of Command Line

#95

Post by VanDerSomebody »

gchpaco wrote: post #27
stass wrote: post #20

Earlier quoted context omitted.

The question is, do you need to handle UTF-8? In most cases of sever management having LATIN1 would suffice, or appropriate localized 8-byte encoding. You can apply the same argument to any other obscure encoding scheme, not just UTF-8. The answer is really to pick the encoding which will suite the most usecases and won't be painful to use.

How is ASCII or Latin-1 somehow not an obscure encoding scheme by your parlance? Latin-1 is less common by quite a bit on the web than UTF-8, and ASCII might be if UTF-8 wasn't a superset. Fact of the matter is people have to get out of the habit of going "oh, that will never be relevant for me", because a) that's unlikely to be true for everybody (for example in a server environment you can't even write perfectly go…

> I know of a man whose first name is Þórr who outright refuses to deal with any organization that will not let him write his name, and I have a hard time disagreeing with him.

I wish I had that luxury sometimes. Here's a pet peeve. I live in France, where people expect everyone to have a one-word family name (it seems). It's really common for people and especially computer systems to "correct" my name (which is of the form Me van der Somebody) to something like Me VANDERSOMEBODY or Me Van Der Somebody. A particular web page (my employer's, actually -- where I have to fill in my name for my "profile page") does the latter, and refuses to allow me to fix it. I have submitted bug reports, and just get WONTFIX back. :(

It's really rude, so I can imagine that for a person called þórr it's a nightmare everywhere except Iceland.

Re: The Art of Command Line

#96

Post by jamespo »

Karunamon wrote: post #41
cmrx64 wrote: post #24

> StrictHostKeyChecking=no And welcome to MITM haven. This is awful advice if you care about the first S in SSH.

Depends on your circumstances, really. If you're in an environment with lots of VM's floating around, being created, destroyed, and so on, dealing with SSH's paranoia (why can't I just dismiss a warning about a host/key mismatch instead of having to edit .known_hosts?) quickly becomes an exercise in frustration for dubious security benefit. (If the enemy is on your LAN and able to manipulate your DNS, you've already…

In these environments you can use server certificates

https://www.digitalocean.com/community/tutorials/how-to-crea...

Re: The Art of Command Line

#97

Post by gitaarik »

One really useful shortcut I learned in bash is Ctrl-/ which is a sort of undo for bash when composing a command. Can't really explain how it works, you should try it out yourself.

Also really handy is Ctrl-Y, which pastes the last cut characters by Ctrl-W, Ctrl-U or Ctrl-K.

Re: The Art of Command Line

#98

Post by anc84 »

natch wrote: post #84

Another one for obscure but useful: jot # print 10 values from 1 to 10, with leading zeros: for n in `jot -w "%04d" 10 1 10`; do echo $n; done

Just use Bash's builtin things:

for n in {0001..0010}; do echo ${n}; done

Re: The Art of Command Line

#99

Post by erikb »

baby wrote: post #77
bdamm wrote: post #15

If you learn bash, and you learn vi, then the next most glorious addition is: set -o vi Then you have vi keys in your shell. And it is marvelous.

or if you learn emacs you have emacs shortcuts by default in shells. which goes against his childish comment on emacs: > Learn Vim (vi). There's really no competition for random Linux editing (even if you use Emacs, a big IDE, or a modern hipster editor most of the time).

At first I thought the same as you, but then I realised that he's not talking about your average editor, but about which editor to use if you SSH into a random web server etc. The thing you use in a foreign environment. That's what "random Linux editing" probably means.

Re: The Art of Command Line

#100

Post by weavie »

stinos wrote: post #82

Fluency on the command line is a skill now often neglected or considered archaic By whom? (honest question: even the most GUI oriented people I know reckon the power of command line skills)

I work in a .Net house. When we had to move to front end development which required using grunt shock from the command line there was plenty of dissent at how we were being forced back into the "dark ages".
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