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Snippets for yer computer needs

Operating Systems

Writing operating systems

http://wiki.osdev.org

POSIX

Standards

Minix

Resources

Android

Keystore

# Create a keystore
keytool -genkey -v -keystore /path/to/example-key.keystore -keyalg RSA -keysize 2048 -alias alias_name -validity 10000
# Get expiration dates in the store
keytool -list -v -keystore keystore.jks

Auto-sign release

Add to ant.properties

key.store=/path/to/example-key.keystore
key.alias=alias_name

Solaris

This includes Solaris derivatives as well, such as OpenSolaris and the Illumos project http://www.brendangregg.com/blog/2017-09-05/solaris-to-linux-2017.html

Solaris

SMF (Service Management Facility)

Clear maintenance mode and restart

svcadm clear <FMRI>

List services

svcs -a

Logs

/var/svc/log

Sun OpenBoot

Boot from CDROM

boot cdrom

Test hardware

test-all

Show banner

banner

Get ethernet address

.enet-addr

Show hardware devices

show-devs

SmartOS

SmartDataCenter

Find VM by alias

sdc-vmapi /vms json -H -c “this.alias && this.alias.match(/riak/)”

Output fwapi rules

sdc-fwapi /rules

Update resolvers

sdc-vmapi /vms/?action=update -d '{ "resolvers": ["8.8.8.8", "8.8.4.4"] }'

OmniOS

https://omnios.org/

OpenBSD

List PCI devices

pcidump -v

Install package

 pkg_add <package>

Add an IP alias to a network interface

ifconfig carp0 inet alias 192.0.1.2 netmask 255.255.255.255

Delete an IP alias

ifconfig carp0 delete 192.0.1.2

Download ports

cd /usr cvs get ports

USB snapshots

dd if=install*.fs of=/dev/sd1c bs=1m

Updates

# See installed patches
syspatch -l
# See uninstalled patches
syspatch -c
# Install any uninstalled patches
syspatch

Securelevels

Edit /etc/rc.securelevel or sysctl kern.securelevel

num desc
-1 permanently insecure
0 insecure
1 secure
2 highly secure

Building from source

See man 8 release

OpenBSD ld.so

# get documentation
man ld.so
# get information about what is getting loaded at run-time
LD_DEBUG=1 ./a.out

trunk

Setup

 ifconfig bge0 up
 ifconfig bge1 up
 ifconfig trunk0 trunkport <proto> bge0 trunkport bge1 \
 192.168.1.1 netmask 255.255.255.0
proto desc
failover Fails over to next link
lacp increases link speed and redundancy, requires lacp-capable switch
loadbalance load-balancing
roundrobin Use round-robin scheduler to distribute traffic

CARP

master advertises on port 112

ifconfig syntax

 ifconfig carpN create
 ifconfig carpN [advbase n] [advskew n] [balancing mode]   \
 [carpnodes vhid:advskew,vhid:advskew,...] [carpdev iface] \
 [[-]carppeer peer_address] [pass passphrase] [state state] [vhid host-id]

Try to become master

# Force master to give up control
ifconfig carp0 down

# Allow preemption
sysctl net.inet.carp.preempt=1

pf

pfctl

flag | command — | — -e | Enable pf -d | Disable pf -nf | parse file, don't load -f | load pf.conf file -sr | show rulesets -ss | show state table -si | show filter stats+counters -sl | show label counters -sa | show everything

General rule syntax

action [direction] [log] [quick] [on interface] [af] [proto protocol] \
[from src_addr [port src_port]] [to dst_addr [port dst_port]] \
[flags tcp_flags] [state] 
action pass/block
direction in/out
quick if packet matches rule, do action and skip rest of rules
af (address family) inet/inet6
protocol udp/tcp/icmp

($ext_if) is shorthand for “use the IP address for the rule” (handy with NAT)

Default deny

block in  all
block out all 

Table containing all IP addresses to firewall

table <firewall> const { self }

Resources

pfsync

sysctl

net.inet.carp.preempt=1

ifconfig

ifconfig em1 10.10.10.2 netmask 255.255.255.0 ifconfig pfsync0 syncdev em1 ifconfig pfsync0 up

Conferences

View lifecycle

iOS web programming

Web Inspector

On Mac

Safari -> Preferences -> Advanced -> Show Develop in menu bar

On iPhone

Settings -> Safari -> Advanced -> Web Inspector

Application Name

<title>WebApp</title>

Launcher icon (iOS 1.1.3+)

Rounded corners, no added shiny (iOS 4.2):

<link rel="apple-touch-icon-precomposed" href="apple-touch-icon-precomposed.png"/>

Added shiny:

With no sizes the default is 57x57 px (Multiple sizes iOS 4.2+)

Startup Image (iOS 3.0+)

<link rel="apple-touch-startup-image" href="/startup.png">

320x460 px, portrait

Have standalone look

<meta name="apple-mobile-web-app-capable" content="yes" />

You might think it’s an innocent meta tag, but in fact it’s a powerful and dangerous meta tag if you add it irresponsibly. You must provide a single page application solution offering back buttons inside the UI -or use location.href instead of normal links if you don’t want them to be opened in the browser instead of your app’s container-.

https://medium.com/@firt/dont-use-ios-web-app-meta-tag-irresponsibly-in-your-progressive-web-apps-85d70f4438cb

That will involve: a) adding back navigation everywhere, b) create a SPA experience or use location.href instead of links for internal navigation, c) if the load process is done in fullscreen mode (navigator.standalone==true), always load the home screen not matter what the stored URL says and please d) don’t suggest me to “download an app” if I’m already inside an app-like experience.

Hide top status bar

NB - must have standalone mode on.

<meta name="apple-mobile-web-app-status-bar-style" content="black" />

Prevent zooming

<meta name="viewport" content="initial-scale=1.0">
<meta name="viewport" content="maximum-scale=1.0">
<meta name="viewport" content="user-scalable=no">
<meta name="viewport" content="width=device-width">

https://developer.apple.com/library/archive/documentation/AppleApplications/Reference/SafariWebContent/ConfiguringWebApplications/ConfiguringWebApplications.html

watchOS

watchOS app bundled in iOS app https://developer.apple.com/library/content/documentation/General/Conceptual/WatchKitProgrammingGuide/Art/architecture_compared_2x.png

Complications

The visual element on the watchface

Notifications

short look - glanceable version of notification content if the wrist remains raised, goes to long look

UI

Key color

stored in Global Tint property of an app’s storyboad

Page-based navigation

Add interface controllers

tvOS

https://developer.apple.com/documentation/tvservices https://developer.apple.com/documentation/avkit https://developer.apple.com/documentation/mediaplayer https://developer.apple.com/documentation/tvmljs

osquery

Get processes where the path no longer exists

select pid,path,uid from processes where on_disk=0;

Fuchsia

https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main

PRIMOS

OS built in FORTRAN