What is something *new* you have learned about Linux within the past 7 days?

igadoter · 02-25-2021, 06:15 PM

Bash manual is terrible. True horror.

shruggy · 02-25-2021, 06:48 PM

You just don't know how to prepare it properly.

igadoter · 02-25-2021, 07:11 PM

Can you learn C from its Backus-Naur grammar description?

shruggy · 02-25-2021, 07:21 PM

Well, it's Bash Reference Manual after all. If you want a guide, there are ABS as well as Greg Wooledge's old and Maarten Billemont's new Bash Guide.

igadoter · 02-25-2021, 07:48 PM

How does it looks like?

Code:

% echo '"'"'*'"'"'
"'*'"

lets try to find out explanation in manual. Perl is nice perlintro , perlfunc etc. Imagine something like that for bash. It also would be nice.

shruggy · 02-25-2021, 08:12 PM

Well,

3.1.2 Quoting in the Bash Manual,
5.1. Quoting Variables in ABS (including examples of weird quoting),
Command arguments and quoting literals in Maarten Billemont's Bash Guide,
3.3. Quoting characters in the Bash Guide for Beginners,
Quoting in the Bourne Shell Scripting Wikibook.

Gemu · 02-27-2021, 07:51 AM

Quote:

Originally Posted by shruggy

Well,

3.1.2 Quoting in the Bash Manual,
5.1. Quoting Variables in ABS (including examples of weird quoting),
Command arguments and quoting literals in Maarten Billemont's Bash Guide,
3.3. Quoting characters in the Bash Guide for Beginners,
Quoting in the Bourne Shell Scripting Wikibook.

There's some good info in there. Thanks for sharing!

hazel · 02-27-2021, 07:54 AM

Quote:

Originally Posted by Gemu

Grub 2's major improvements over grub legacy

1. it offers Script support including conditional statements and functions.

It's the complexity of GRUB2 that I loathe. What's wrong with just a simple menu that doesn't have to be rewritten every time you boot?

Gemu · 02-27-2021, 10:16 AM

Quote:

Originally Posted by hazel

It's the complexity of GRUB2 that I loathe. What's wrong with just a simple menu that doesn't have to be rewritten every time you boot?

It is more complicated than grub legacy. What I've found is to back up all your working grub2 menuentyrs and keep them forever.

And at least on USB's you can copy the ones you need over to the grub.cfg, edit it to reflect USB being (hd0, msdos1) at boot time and they work without ever running update-grub.

I have grub2 thumb drives that will boot anything I have installed on my desktop HD and on the USB itself.
Windows 10 on sdb2, Knoppix 8.6.1 on sdb4, Ubuntu on sda2, Mint on sda4.

With grub legacy you could edit the boot menu during boot and once booted edit the menu.lst to how you made it boot and it simply worked next time around. Grub2 will do the same on USBs, the menu's are just more complex.

Bonzoo · 02-27-2021, 10:23 AM

A few days ago I watched a vidtube ad a guy said Tux Sux . Some guy named Lameduck if I remember correctly ?

jefro · 02-27-2021, 06:44 PM

rpm2cpio.

Never needed it before today.

shruggy · 02-28-2021, 08:07 AM

It's not too hard to emulate rpm2cpio with a shell script. Actually, rpm comes with such a script installed under /usr/lib/rpm/rpm2cpio.sh.

Code:

#!/bin/sh
set -e
export LC_ALL=C
file -b "$1" | grep -q ^RPM || { echo "Usage: $0 <file.rpm>" >&2; exit 1;}
[ -t 0 ] || { echo This script cannot read from stdin >&2; exit 2;}
pkg=$1

skip_hdr_struct() {
  align=$1 # flag: do we need alignment padding to 8-byte boundary?
  set -- `hexdump -s$((off+8)) -n8 -e'"0x" 4/1 "%02X" " "' $pkg`
  : $((off+=16+16*$1+$2+(align?-$2&7:0))) # hsh+16*idx+data[+align8_padding]
}

off=96 # size of RPM lead
skip_hdr_struct 1 # skip RPM signature (+ alignment padding)
skip_hdr_struct 0 # skip RPM header

EXTRACTOR="dd if=$pkg ibs=$off skip=1"
COMPRESSOR=`($EXTRACTOR count=1 | file -b - | tr A-Z a-z) 2>/dev/null`
case $COMPRESSOR in
  gzip\ *|bzip2*|xz\ *|zstan*) DECOMPRESSOR="${COMPRESSOR%% *} -dc";;
                     *cpio\ *) DECOMPRESSOR=cat;;
                            *) DECOMPRESSOR='lzma -dc';; # assume LZMA
esac
$EXTRACTOR 2>/dev/null | $DECOMPRESSOR

Chuck56 · 02-28-2021, 08:52 AM

I've used KDE since 2005 & never knew about Yakuake. Yikes, must be a big rock I'm crawling out from under!

I've used Konsole almost exclusively up until last week when I hit F12 by mistake and Yakuake slid down on my monitor. It's Konsole based so my transition was almost immediate. A few tweaks of the settings and I have a new fav X Terminal Emulator.

HappyTux · 03-08-2021, 10:44 PM

The "type" command found while searching for way to know what a function was in the shell like you can do with alias alias_name and it will show you what it is. Well the type command does that with telling you what the function is short for.

Code:

zeus@buster-raspi:~$ type f2
f2 is a function
f2 () 
{ 
    find "$1" -name "*$2*"
}

hazel · 03-14-2021, 04:26 AM

I've been beefing in another thread about shift-page scrolling on Linux consoles not working with the latest kernels and someone thought I was referring to graphical terminals. In fact I had no idea that you could use shift-page in a graphical terminal; I always use the scrollbox to scroll. So I just tried it and it works. Not that that solves my original problem!