Pure Bash Bible: A collection of pure bash alternatives to external binaries

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Pure Bash Bible: A collection of pure bash alternatives to external binaries unix github.com
via atondwal 19 days ago | cached | 8 comments

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dmytrish edited 19 days ago | link
This list does not mention the most surprising (and a bit disturbing) bash feature for me: it can open tcp/udp sockets on its own [0] through a feature called “special redirects” (there’s no actual filesystem involved here):
```
$ (exec 3<>/dev/tcp/www.google.com/80 ; 
echo "GET /search?q=bash+madness HTTP/1.0" >&3; 
echo >&3; 
cat <&3 ) | less
```
[0] https://dmytrish.net/blog/en/bash-tcp
2

andyc 19 days ago | link

I scanned over this, and OSH [1] should support basically everything here. If it doesn’t, feel free to file a bug!

https://github.com/oilshell/oil/issues

Hm now that I look more at the repo, it looks like this would be a good test: https://github.com/dylanaraps/pure-bash-bible/blob/master/test.sh

[1] http://www.oilshell.org/blog/2018/07/23.html
2
kn 19 days ago | link
Lots of things can already be done with portable sh code. typeset for example is quite powerful but mentioned nowhere in the repo:
```
$ var=VaL; typeset -l lvar=$var; typeset -u uvar=$var
$ echo $lvar $uvar
val VAL
```
In fact, this builtin is often wrapped by the shell itself, at least in OpenBSD’s ksh:
```
$ alias | fgrep typeset
autoload='typeset -fu'
functions='typeset -f'
integer='typeset -i'
local=typeset
```
1. 2
  izabera 18 days ago | link
  typeset is not posix
  
  posix sh has no way to do what typeset -f does
  
  bash has no way to do what typeset -fu does in your ksh
  
  typeset -i doesn’t really have the same effect in bash and ksh
  
  the posix way to convert a string to lowercase/uppercase involves tr or awk
  
  most popular shells support local, but it’s not posix either
  
  “portable sh code” != “it works on my openbsd”
  1. 1
    
    kn 18 days ago | link
    
    Note how I did not speak of POSIX; you mistake the ksh example as general assumption. My reply to pl’s comment tells you what I meant with “portable” (admittedly, wording was a bit misleading).
    1. 1
      
      izabera 17 days ago | link
      
      what’s your definition of portable?
2. 1
  
  pl 18 days ago | link
  
  What do you mean with portable sh code? I just tried it with dash and it has no typeset built in.
  1. 2
    
    kn 18 days ago | link
    
    At least available in Bourne and Korn shell derivatives; (Debian’s) Almquist Shell does not implement that particular builtin.