watch – execute a program periodically

commandline session

following commandline session may not be accurate.

$vmstat
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
 1  0      0 2246368  32720 497284    0    0   217    10  236  436  3  1 92  3
$watch vmstat
$watch -n 0.5 vmstat
$watch -n 0.5 iostat
$watch -n 0.5 iostat
$iostat
Linux 3.12.0 (debian) 	Friday 08 November 2013 	_x86_64_	(2 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           6.64    0.01    2.31    1.80    0.00   89.24

Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
sda               8.82       272.09        51.03     696015     130532

$

the following video tutorial content may not be accurate


GNU/Linux Commands for Beginners : alias

this tutorial content may not be accurate

GNU/Linux Terminal – File Permissions! (Chmod, Chown and Chgrp)

this tutorial content may not be accurate

How To Apply a Patch To The Linux Kernel Stable Tree

How Linux is Built

file — determine file type

commandline session

$ls
faq  favicon.ico  index.html  kernel.css  mirrors  pub	robots.txt
$file kernel.css
kernel.css: ASCII text
$file -l | head
Set 0:
Binary patterns:
Text patterns:
Set 1:
Binary patterns:
Text patterns:
Set 0:
Binary patterns:
Strength = 340 : sc68 Atari ST music []
Strength = 340 : T64 tape Image []
$file -l | tail
Strength =  28 : exported SGML document text []
Strength =  20 : Java source [text/x-java]
Strength =  20 : script text executable []
Strength =  18 : a []
Strength =  17 : a []
Strength =  12 : Perl5 module source text []
Strength =   2 : Tcl script []
Set 1:
Binary patterns:
Text patterns:
$



readelf – Displays information about ELF files

commandline session

$readelf  -I /bin/ping

Histogram for `.gnu.hash' bucket list length (total of 3 buckets):
 Length  Number     % of total  Coverage
      0  0          (  0.0%)
      1  0          (  0.0%)      0.0%
      2  0          (  0.0%)      0.0%
      3  3          (100.0%)    100.0%
$readelf  -a /bin/ping | head
ELF Header:
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           Advanced Micro Devices X86-64
  Version:                           0x1
$readelf  -a /bin/ping | head -n 20
ELF Header:
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           Advanced Micro Devices X86-64
  Version:                           0x1
  Entry point address:               0x402ac0
  Start of program headers:          64 (bytes into file)
  Start of section headers:          38200 (bytes into file)
  Flags:                             0x0
  Size of this header:               64 (bytes)
  Size of program headers:           56 (bytes)
  Number of program headers:         9
  Size of section headers:           64 (bytes)
  Number of section headers:         27
  Section header string table index: 26
$