which [-a] args

commandline session

$ 4.2.36 4 501---> which
$ 4.2.36 5 502---> which -h
Illegal option -h
Usage: /usr/bin/which [-a] args
$ 4.2.36 6 503---> which ls
/bin/ls
$ 4.2.36 7 504---> which -a ls
/bin/ls
$ 4.2.36 8 505---> which -a top
/usr/bin/top
$ 4.2.36 9 506---> which  top
/usr/bin/top
$ 4.2.36 10 507---> echo $?
0
$ 4.2.36 11 508---> which  to
$ 4.2.36 12 509---> echo $?
1
$ 4.2.36 13 510---> which -k top
Illegal option -k
Usage: /usr/bin/which [-a] args
$ 4.2.36 14 511---> echo $?
2
$ 4.2.36 15 512--->

PHILOSOPHY

  • MAKE SOLUTIONS THAT JUST WORKS
  • DO EASY WORK IN A PLAYFUL WAY
  • KNOWLEDGE AND SKILL DEVELOPED FROM PLAY CAN BE USED FOR WORK.
    HENCE KNOWLEDGE FOR WORK CAN BE A BYPRODUCT OF PLAY
  • PLAY NEEDS LEARNING PROCESS
  • EXCITEMENT CAN BE INTEGRATED BY SHARING KNOWLEDGE
  • IT IS NOT ALWAYS NECESSARY TO FINISH THE CURRENT TASK BEFORE MOVING TO A NEW TASK
  • KEEP INTERMEDIATE LEVEL ON ALL WORKS AND UPDATE THE LEVEL
  • THERE IS NO SUCH THING ALWAYS AS RIGHT OR WRONG.SOMETIMES THINGS MAY OR MAY NOT HAPPEN ACCORDING TO OUR CALCULATION
  • ONE MAY NOT BECOME GREAT BY ATTACHING GREAT THINGS TO ONESELF

sed . regular expressions

commandline session

$ 4.1.5 1 270---> echo "fastest 1000 cars" | sed "s/1000/2000/"
fastest 2000 cars
$ 4.1.5 2 271---> echo "fastest 1000 cars" | sed "s/1*/2000/"
2000fastest 1000 cars
$ 4.1.5 3 272--->
$ 4.1.5 3 272---> echo "fastest 1000 cars" | sed "s/2*/2000/"
2000fastest 1000 cars
$ 4.1.5 4 273---> echo "fastest 1000 cars" | sed "s/'2'/2000/"
fastest 1000 cars
$ 4.1.5 5 274---> echo "fastest 1000 cars" | sed "s/'1'/2000/"
fastest 1000 cars
$ 4.1.5 6 275---> echo "fastest 1000 cars" | sed "s/1/2000/"
fastest 2000000 cars
$ 4.1.5 7 276---> echo "fastest 1000 cars" | sed "s/1?/2000/"
fastest 1000 cars
$ 4.1.5 8 277---> echo "fastest 1000 cars" | sed "s/?1/2000/"
fastest 1000 cars
$ 4.1.5 9 278--->

type—Display a Command’s Type

Commandline session

$type
$type ls
ls is /bin/ls
$type Xorg
Xorg is /usr/bin/Xorg
$type  hey
bash: type: hey: not found
$type  ls -l
ls is /bin/ls
bash: type: -l: not found
$type  pwd
pwd is a shell builtin
$type  shopt
shopt is a shell builtin
$type  time
time is a shell keyword
$type  times
times is a shell builtin
$type  pstree
pstree is /usr/bin/pstree
$type  man
man is /usr/bin/man
$type  file
file is /usr/bin/file
$type  type
type is a shell builtin
$

debug : using iw command ( netlink debugging )

ABOUT Netlink

The Netlink socket family is a Linux kernel interface used for inter-process communication (IPC) between both the kernel and userspace processes, and between different userspace processes, in a way similar to the Unix domain sockets. Similarly to the Unix domain sockets, and unlike INET sockets, Netlink communication cannot traverse host boundaries. However, while the Unix domain sockets use the file system namespace, Netlink processes are usually addressed by process identifiers (PIDs). [3]

Netlink is designed and used for transferring miscellaneous networking information between the kernel space and userspace processes. Networking utilities, such as the iproute2 family and the utilities used for configuring mac80211-based wireless drivers, use Netlink to communicate with the Linux kernel from userspace. Netlink provides a standard socket-based interface for userspace processes, and a kernel-side API for internal use by kernel modules. Originally, Netlink used the AF_NETLINK socket family.

Netlink is designed to be a more flexible successor to ioctl; RFC 3549 describes the protocol in detail.

TYPICAL COMMANDLINE SESSION
[bash]
$iw –debug wlan0 info
— Debug: Sent Message:
————————– BEGIN NETLINK MESSAGE —————————
[HEADER] 16 octets
.nlmsg_len = 28
.nlmsg_type = 22 <0x16>
.nlmsg_flags = 5 <request,ACK>
.nlmsg_seq = 1344974880
.nlmsg_pid = 41009
[PAYLOAD] 12 octets
05 00 00 00 08 00 03 00 02 00 00 00 …………
————————— END NETLINK MESSAGE —————————
— Debug: Received Message:
————————– BEGIN NETLINK MESSAGE —————————
[HEADER] 16 octets
.nlmsg_len = 64
.nlmsg_type = 22 <0x16>
.nlmsg_flags = 0 <>
.nlmsg_seq = 1344974880
.nlmsg_pid = 41009
[PAYLOAD] 48 octets
07 01 00 00 08 00 03 00 02 00 00 00 08 00 01 00 00 00 ………………
00 00 0a 00 04 00 77 6c 61 6e 30 00 00 00 08 00 05 00 ……wlan0…….
02 00 00 00 08 00 2e 00 05 00 00 00 …………
————————— END NETLINK MESSAGE —————————
Interface wlan0
ifindex 2
type managed
wiphy 2
— Debug: Received Message:
————————– BEGIN NETLINK MESSAGE —————————
[HEADER] 16 octets
.nlmsg_len = 36
.nlmsg_type = 2 <error>
.nlmsg_flags = 0 <>
.nlmsg_seq = 1344974880
.nlmsg_pid = 41009
[ERRORMSG] 20 octets
.error = 0 "Success"
[ORIGINAL MESSAGE] 16 octets
.nlmsg_len = 16
.nlmsg_type = 22 <0x16>
.nlmsg_flags = 5 <request,ACK>
.nlmsg_seq = 1344974880
.nlmsg_pid = 41009
————————— END NETLINK MESSAGE —————————
$

[/bash]

NOTE
These Notes Comes With NO WARRANTY

Debug Using Application/Command  That Support Debug Mode.
I Call This "Inbuilt Debugging"

LINK
https://en.wikipedia.org/wiki/Netlink

$_ indicates exactly the last parameter of your last command (GNU Bash)

commandline session

$ 4.2.29 8 507---> ls
Algorithms     bookmark  bugs-general  debian-howtos  firewall	kernel	  linux    README
beautifulwork  books	 config-files  Docs	      https:	language  ovlfose
$ 4.2.29 9 508---> ls $_
ls: cannot access ls: No such file or directory
$ 4.2.29 10 509---> ls vm
ls: cannot access vm: No such file or directory
$ 4.2.29 11 510---> ls $_
ls: cannot access vm: No such file or directory
$ 4.2.29 12 511---> ls Docs
23-awesome-less-known-linuxunix-command-chaining-examples.html	linux-asm.txt  test.html  xargs.html
cairo.pdf							rtl8139d.pdf   wpdb.html
$ 4.2.29 13 512---> pwd
/home/jeffrin/shelter/symmel
$ 4.2.29 14 513---> ls Docs
23-awesome-less-known-linuxunix-command-chaining-examples.html	linux-asm.txt  test.html  xargs.html
cairo.pdf							rtl8139d.pdf   wpdb.html
$ 4.2.29 15 514---> cd $_
$ 4.2.29 16 515---> pwd
/home/jeffrin/shelter/symmel/Docs
$ 4.2.29 17 516--->

debug : Wireless LAN with Realtek and Dlink

things i looked

  • BIOS checkup related to ethernet controller
  • Details of network and network card using iwlist command
  • Security Mechanism Supported By Network Card and Router
  • Looked for Matching the standards Like security mechanisms related.
  • Looked for matching standards in Wireless like IEEE 802.11bg

Debian Research

These Notes Comes With NO WARRANTY
Using iwlist command in debian

There are various channels holding diffrent frequencies
in a single signal.

findup . find dUPlicate files.

commandline session

$ 4.1.5 3 249---> cd
$ 4.1.5 4 250--->
$ 4.1.5 4 250---> cd .mozilla/
$ 4.1.5 5 251---> /usr/share/fslint/fslint/findup
firefox/625qvjz5.default/bookmarkbackups/bookmarks-2012-08-09.json
firefox/625qvjz5.default/bookmarkbackups/bookmarks-2012-08-10.json

firefox/625qvjz5.default/Cache/B/32/B73FDd01
firefox/625qvjz5.default/blocklist.xml

firefox/625qvjz5.default/Cache/2/90/C2EE2d01
firefox/625qvjz5.default/Cache/5/60/BF572d01
firefox/625qvjz5.default/Cache/A/D8/DB996d01
firefox/625qvjz5.default/Cache/B/F2/AFA8Fd01

firefox/625qvjz5.default/Cache/A/FE/A20B7d01
firefox/625qvjz5.default/Cache/B/F3/3B077d01

firefox/625qvjz5.default/Cache/3/F0/215E4d01
firefox/625qvjz5.default/Cache/A/ED/CB4DCd01

firefox/625qvjz5.default/Cache/7/83/3D82Dd01
firefox/625qvjz5.default/Cache/C/E6/E2E3Ad01
firefox/625qvjz5.default/Cache/F/08/7726Dd01

firefox/625qvjz5.default/Cache/6/85/8A7FEd01
firefox/625qvjz5.default/Cache/9/47/C031Dd01

firefox/625qvjz5.default/Cache/5/33/312ACd01
firefox/625qvjz5.default/Cache/B/FA/7E28Bd01
firefox/625qvjz5.default/Cache/E/B6/83C07d01
firefox/625qvjz5.default/Cache/E/C5/0FDC3d01

firefox/625qvjz5.default/Cache/8/E0/AE2A7d01
firefox/625qvjz5.default/Cache/9/2F/5168Ad01

firefox/625qvjz5.default/Cache/2/4F/7E1CCd01
firefox/625qvjz5.default/Cache/A/93/23EA4d01

firefox/625qvjz5.default/Cache/E/33/3377Ad01
firefox/625qvjz5.default/Cache/F/37/510091d01

firefox/625qvjz5.default/Cache/1/71/00FA9d01
firefox/625qvjz5.default/Cache/2/16/736D7d01
firefox/625qvjz5.default/Cache/4/4C/254FFd01
firefox/625qvjz5.default/Cache/A/E7/06BBAd01

firefox/625qvjz5.default/Cache/A/15/E56B7d01
firefox/625qvjz5.default/Cache/E/81/93992d01

firefox/625qvjz5.default/Cache/0/8B/DBA1Ad01
firefox/625qvjz5.default/Cache/5/01/13511d01

firefox/625qvjz5.default/Cache/2/2F/F92F8d01
firefox/625qvjz5.default/Cache/2/7D/8C9B6d01
firefox/625qvjz5.default/Cache/2/C5/78B2Dd01
firefox/625qvjz5.default/Cache/3/36/C2514d01
firefox/625qvjz5.default/Cache/4/22/79D68d01
firefox/625qvjz5.default/Cache/5/22/53D9Bd01
firefox/625qvjz5.default/Cache/6/B9/D1372d01
firefox/625qvjz5.default/Cache/8/42/729F8d01
firefox/625qvjz5.default/Cache/B/2E/CF80Ad01
firefox/625qvjz5.default/Cache/C/48/0646Cd01
firefox/625qvjz5.default/Cache/C/9B/B706Dd01
firefox/625qvjz5.default/Cache/D/73/68884d01

firefox/625qvjz5.default/Cache/6/BA/8A07Cd01
firefox/625qvjz5.default/Cache/6/C5/FA606d01
firefox/625qvjz5.default/Cache/D/F5/7A346d01
firefox/625qvjz5.default/Cache/E/3E/55907d01
$ 4.1.5 6 252--->