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Ask HN: How can I get better at bash?

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Re: Ask HN: How can I get better at bash?

#171

Post by vram22 »

SEJeff wrote: post #101

As silly as it sounds, when I was a new Unix SysAdmin, I read the entirety of "man 1 bash", which includes all bash builtins. I found that it improved by bash-foo 100x simply by knowing about so many of the utilities. I also took some cliff notes for things that seemed generally useful. I did it for an hour or so a night for a week or so. That being said, a few of my personal favorites to memorize: * Parameter expans…

Some good advice there.

One thing I have found that less people seem to know, is that the Unix metacharacters are expanded by the shell (bash etc.) not by individual commands. What this implies is that any command, whether built-in or written by you (in C, bash, Python or any other language), has metacharacter support automatically. That is, things like the file globbing/wildcard characters like *, ?, and [ ranges ].

This was not originally true on DOS (as a counterexample) and not sure whether it is true on Windows today (haven't checked), though I did notice that more commands seem to support wildcards in Windows nowadays.

Also, for some years now, Windows too has had redirections like:

command >file.txt 2>&1

(redirect stderr (2) to the same destination that stdout (1) is pointing to, i.e. file.txt), which Unix had from the start.

Re: Ask HN: How can I get better at bash?

#172

Post by vram22 »

This script can be useful to save man pages (not just the bash man page, any man page) as text - removing all the control characters which are used for printing with formatting (bold, etc.):

m, a Unix shell utility to save cleaned-up man pages as text:

https://jugad2.blogspot.in/2017/03/m-unix-shell-utility-to-s...

I've been using it from earlier Unix versions, where these formatted man pages (nroff/troff-formatted) were more of an issue. Also works if you want to open the text form of the man page in vi or vim, for reading, searching, etc.

Re: Ask HN: How can I get better at bash?

#173

Post by vram22 »

SEJeff wrote: post #101

As silly as it sounds, when I was a new Unix SysAdmin, I read the entirety of "man 1 bash", which includes all bash builtins. I found that it improved by bash-foo 100x simply by knowing about so many of the utilities. I also took some cliff notes for things that seemed generally useful. I did it for an hour or so a night for a week or so. That being said, a few of my personal favorites to memorize: * Parameter expans…

>All of test(1) as you can use them in any if statement (/usr/bin/[ is a real command!):

Yes, and not only in an if statement. You can also use test or [ command in commands of the form:

test condition && commmand2

or

test condition || command2

which will only work if the condition is true or false, respectively (IIRC, need to check this).

Re: Ask HN: How can I get better at bash?

#174

Post by mobilethrow »

yebyen wrote: post #159
uhhfcuvv wrote: post #152

Earlier quoted context omitted.

This is terrible advice, if you expect your PATH to be something, just set it at the top of the script and be done with it. No need to make it 100 times harder to read.

Why even expect binaries to be in the same place on different systems with different default PATHs? Know how many times I've seen problems caused by (#!/usr/bin/bash|#!/bin/bash) pointing to the wrong place? After reading this thread though, I'm not sure I want to suggest people write `#!/usr/bin/env bash` either... since that depends on the path being correctly set, and bash being in the path!

I've started to dislike /usr/bin/env too. At least use -i. Otherwise you're one PATH manipulation away from executing a malicious program as your intended shell.

Re: Ask HN: How can I get better at bash?

#179

Post by oddly »

Do some puzzles(wargames). For example: http://overthewire.org/wargames/

It will make you search for several special use cases and will give you some experience with the command line. Basically, you SSH into a box, solve a problem and the solution for that problem is the password for the next SSH connection for the next problem.

This one is for beginners: http://overthewire.org/wargames/bandit/

Re: Ask HN: How can I get better at bash?

#180

Post by eof »

sevensor wrote: post #94
eof wrote: post #77

Earlier quoted context omitted.

I think this is the right answer, assuming OP actually wants to get better at bash and not route around his original question by learning stuff that isn't bash. I use bash/shell scripts frequently and have many running 'in production' as cron jobs th at run various jobs or manipulate data for other jobs to run on. One thing I really like about pure shell is that it's extremely portable and transparent about what it's…

I couldn't begin to say how many times I've typed "help test". It's a lot. I usually get the answer I'm looking for, when it comes to conditionals.

TIL. even faster than the google
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