THEME: POWERSHELL

          But why use PowerShell.. on Linux?  
          One reason is the beauty of the language and   
          the powerful capability of the object-piping*.  
              
          *) https://www.starwindsoftware.com  
              /blog/using-powershell-on-linux

Install Powershell on Linux Debian 11

(https://docs.microsoft.com/en-us/powershell/scripting/install/install-debian?view=powershell-7.2)

  1. Install up-pwsh:

    #!/bin/bash  
  
if [ "$UID" -ne "0" ]  
then  
    echo "You are not root, exiting.."  
    exit 1  
fi  
  
apt update && apt -y upgrade && apt install -y wget  
URL="https://packages.microsoft.com/config/debian/"  
URL+="11/packages-microsoft-prod.deb"  
wget $URL  
dpkg -i packages-microsoft-prod.deb  
apt update  
apt install -y powershell  
rm -f packages-microsoft-prod.deb

  2. Remove down-pwsh:

    #!/bin/bash  
  
if [ "$UID" -ne "0" ]  
then  
    echo "You are not root, exiting.."  
    exit 1  
fi  
  
# Remove Microsoft repo  
rm -f /etc/apt/sources.list.d/microsoft-prod.list  
apt update  
# Remove PowerShell  
apt autoremove --purge -y powershell 2> /dev/null  
rm -rf /usr/local/share/ca-certificates/

USEFUL TIPS

..Well now, what shall I talk about? There are, of course, any number of things I could talk about. I could take the egotistical approach and talk about myself, elucidating all those quirks of genetics and upbringing that brought me to the place of creating Perl, as well as making a fool of myself in general. That might be entertaining, at least to me.

.."Do one thing and do it well" was the rallying cry, and with one stroke, shell programmers were condemned to a life of muttering and counting beads on strings (which in these latter days have come to be known as pipelines).. This was when I made my small contribution to saving the world. I was rolling some of those very beads around in my fingers one day and pondering the hopelessness (and haplessness) of my existence, when it occurred to me that it might be interesting to melt down some of those mystical beads and see what would happen to their Magic if I made a single, slightly larger bead out of them. So I fired up the old Bunsen burner, picked out some of my favorite beads, and let them melt together however they would. And lo! the new Magic was more powerful than the sum of its parts and parcels.

..The Amulet isn't exactly beautiful though -- in fact, up close it still looks like a bunch of beads melted together. Well, all right, I admit it. It's downright ugly. But never mind that. It's the Magic that counts.

Larry Wall
September, 1993
https://www.cs.ait.ac.th/~on/O/oreilly/perl/learn32/prf1_01.htm

.. будучи на кухне, пришла одна мысль на тему предыдущего выступления:

Я слил остатки супов в одну кастрюлю и размешал -- получилось вполне съедобно. Про историю пиццы и фруктового желе даже не стану вникать в детали -- "..из всего, что осталось". Это Perl!.. Но я пошел дальше и вывалил все три полученных блюда в одно корыто. Это (вы подумали помои?) Powershell!, решил я.

1..6 | % { 1,2,8,10,16 | % { $_ }}
1 | % { $_ ? "too much" : "not enough" }
too much
0 | % { $_ ? "too much" : "not enough" }
not enough

Для начала уясним, что echo является синонимом Write-Output.
Write-Host является продвинутым аналогом Write-Output.

write-host hi -NoNewline "welt"
  1. https://pwsh.ru/аналог-echo-в-powershell/?ysclid=laut0vennn283632690
  2. https://devblogs.microsoft.com/powershell/how-does-select-string-work-with-pipelines-of-objects/

Easiest way to Shuffle an Array with PowerShell

 1..30 | Sort-Object {Get-Random}

https://ilovepowershell.com/2015/01/24/easiest-way-shuffle-array-powershell/

Get-Alias | out-string -stream | Select-string "wri"
Get-Command | Where {$_.NAME -match "Wri"}

https://devblogs.microsoft.com/powershell/how-does-select-string-work-with-pipelines-of-objects/

DIFFERENT SAMPLE TASKS (POWERSHELL PORTFOLIO)

  1. IO

    PS> $x=Read-Host  
something weird  
PS> Write-Host $x  
something weird

  2. binary to decimal

    "10000111110" | % { [convert]::ToInt64($_,2) }

    output

    1086

  3. split string by regular expression

    PS> "1101  11 10010" -split "\s+"

    output

    1101  
11  
10010

  4. read tape of c∈{0,1,space}c \in \{ 0, 1, \text{space} \}

    PS> "1000100  1000110 1001011" -split "\s+" | `  
     % { [char][convert]::ToInt32($_,2) }

    output

    D  
F  
K

  5. pass through pipe

    % -- ForEach commandlet
    $_ -- default variable
    {} -- block, everything created inside the block, dies on exit block

    PS> gc .\ansi.txt

    output

    In the town where I was born  
Lived a man who sailed to sea  
And he told us of his life  
In the land of submarines

    output

    gc ./ansi.txt | % { $_ }

    output

    In the town where I was born  
Lived a man who sailed to sea  
And he told us of his life  
In the land of submarines

  6. display verse verically (in one column)

    PS> cat .\ansi.txt | % { $_.toCharArray() | % { $_ } }

    out

    I  
n  
..  
s

  7. converts text in ansi.txt file to string of binaries

    $s = ""  
gc .\ansi.txt |    
% { $_.toCharArray() |   
% { $s+=[Convert]::ToString([int]$_,2); $s+=" " } }  
$s

    out

    1001001 1101110 100000 1110100 1101000 1100101 100000  
1110100 1101111 1110111 1101110 100000 1110111 1101000   
1100101 1110010 1100101 100000 1001001 100000 1110111    
1100001 1110011 100000 1100010 1101111 1110010 1101110   
1001100 1101001 1110110 1100101 1100100 100000 1100001   
100000 1101101 1100001 1101110 100000 1110111 1101000   
1101111 100000 1110011 1100001 1101001 1101100 1100101   
1100100 100000 1110100 1101111 100000 1110011 1100101   
1100001 1000001 1101110 1100100 100000 1101000 1100101   
100000 1110100 1101111 1101100 1100100 100000 1110101   
1110011 100000 1101111 1100110 100000 1101000 1101001   
1110011 100000 1101100 1101001 1100110 1100101 1001001   
1101110 100000 1110100 1101000 1100101 100000 1101100   
1100001 1101110 1100100 100000 1101111 1100110 100000   
1110011 1110101 1100010 1101101 1100001 1110010 1101001   
1101110 1100101 1110011

  8. shorter if

    $CarColor = 'Blue'  
$x = @{   
  $true = 'The car color is blue';   
  $false = 'The car color is not blue'  
}  
$x[$CarColor -eq 'Blue']

    output

    The car color is blue

  9. string length

    PS> "abc" |  % { $_.length }

    output

    3

  10. Text to binaries and back s.ps1

$a = $s = ""  
Get-Content .\ansi.txt |  
% { $_.toCharArray() |  
    % { $s+=[Convert]::ToString([int]$_,2); $s+=" " }  
    $s+="1010 "  
}  
$s  
"   oooooooo   "  
$s -split "\s+" |  
% {  
  if ($_.length -ne 0) {  
    $a += [char][Convert]::ToInt32($_,2)  
  }  
}  
$a

output

PS> ./s.ps1  
1001001 1101110 100000 1110100 1101000 1100101 100000   
1110100 1101111 1110111 1101110 100000 1110111 1101000      
1100101 1110010 1100101 100000 1001001 100000 1110111      
1100001 1110011 100000 1100010 1101111 1110010 1101110   
1010 1001100 1101001 1110110 1100101 1100100 100000   
1100001 100000 1101101 1100001 1101110 100000 1110111   
1101000 1101111 100000 1110011 1100001 1101001 1101100   
1100101 1100100 100000 1110100 1101111 100000 1110011   
1100101 1100001 1010 1000001 1101110 1100100 100000   
1101000 1100101 100000 1110100 1101111 1101100 1100100   
100000 1110101 1110011 100000 1101111 1100110 100000   
1101000 1101001 1110011 100000 1101100 1101001 1100110   
1100101 1010 1001001 1101110 100000 1110100 1101000   
1100101 100000 1101100 1100001 1101110 1100100 100000   
1101111 1100110 100000 1110011 1110101 1100010 1101101   
1100001 1110010 1101001 1101110 1100101 1110011 1010  
   oooooooo  
In the town where I was born  
Lived a man who sailed to sea  
And he told us of his life  
In the land of submarines

  1. Validators

    1. Boolean

      $false -match '^(True|False)$'

      output:

      True

    2. Integer

      '+2718281828' -match '^[+-]?[1-9][0-9]*|0$'

    3. Real. If you also want to match numbers with exponents, you can use:

      '-1.45e-3' -match   
  '^[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?$'

      output:

      True

  2. Learn AWK/ARDUINO/PROCESSING template: BEGIN LOOP END
    include the functions into your session.
    Learn $input variable.

    PS> gc myfunc.ps1  
Function Echo-Pipe {  
  Begin { "revisiting AWK BEGIN" }  
  # Executes once for each pipeline object  
  Process { echo $_  }  
  End { "revisiting AWK END" }  
}  

Function Echo-Pipe2 { foreach ($i in $input) { $i } }  

PS> . .\myfunc.ps1  
PS> cat data.txt | Echo-Pipe

    output

    revisiting AWK BEGIN  
In the town where I was born  
Lived a man who sailed to sea  
And he told us of his life  
In the land of submarines  
revisiting AWK END  

    PS> gc data.txt | Echo-Pipe2

    output:

    In the town where I was born  
Lived a man who sailed to sea  
And he told us of his life  
In the land of submarines

  3. Important ? Commandlet -- Where-Object
    4 ways to operate with Windows Services.

    services.msc  

Get-Service | ? {$_.StartType -eq "Automatic"}  
PS#> Start-Service sshd  
PS#> Set-Service -Name sshd -StartupType 'Automatic'  

CMD#> net start|stop|pause <servicename>  
CMD#> sc start|stop|create|delete|query <servicename>

    *) ? -- Where-Object

  4. Search

    PS> gc .\ansi.txt  

    In the town where I was born  
Lived a man who sailed to sea  
And he told us of his life  
In the land of submarines  

    PS> gc .\ansi.txt | Select-String -Pattern '^[^AEIOU]'  

    Lived a man who sailed to sea  
^

  5. Search and Replace. BackReference and BackTick.

    PS> Write-Output "ABA" | % { $_ -Replace "(B)","`$1`$1" }  
ABBA

  6. Coloring text

    Basic idea -- Store Escape character in variable first:

    PS\> $esc = "$([char]27)"

    Synthetic command (visible colors):

    "$esc[90mDARK$esc[91mRED$esc[92mGREEN$esc[94mBLUE" + `  
"$esc[93mYELLOW$esc[96mCYAN$esc[95mMAGENTA$esc[0m"

    Reset to defaults (Reset all):

    $esc[0m

  7. output format with Out-File

    PS> Write-Output "kukarekuuu..!" |   
    Out-File demo -Encoding ascii  
PS> Get-Content demo  
kukarekuuu..!

(also: ascii, bigendianunicode, default, oem, string, unicode, unknown, utf32, utf7, utf8)

  1. Read file line by line in PowerShell

    $regex = "w"  
PS> gc .\ansi.txt | ? {$_ -match $regex} | % { $_ }  
In the town where I was born  
Lived a man who sailed to sea

  2. Read argument

    PS> args.ps1  
gc $args[0]  
PS> .\args.ps1 .\file.txt  

    In the town where I was born  
Lived a man who sailed to sea  
And he told us of his life  
In the land of submarines

  3. Read variable from file

    $text = gc $filePath -Raw

  4. Write variable to a file

    $hello | Out-File c:\debug.txt

  5. Arguments

    foo.ps1

    param(    
[Parameter(  
    Position=0,   
    Mandatory=$true,   
    ValueFromPipeline=$true,  
    ValueFromPipelineByPropertyName=$true)  
]  
[Alias('Arguments')]  
[String[]]$Args  
)   
    foreach($path in $Args) {  
  Write-Host "file path is: $path"  
}

  6. Best Practices:

    1. !: Use full cmdlet name in scripts (not alias)

    Get-Command -CommandType Alias ~300                                                                             
  % -> ForEach-Object  
  ? -> Where-Object  
  echo -> Write-Output  
  gc ->  Get-Content

    2. B: Use named parameters in scripts (not positional
    and partial parameters)

    3. T: Avoid Write-Host

    8. !: Use WhatIf and Confirm parameters
    WhatIf : Only displays the objects that would be affected and what changes would be made to those objects (without the worry of modifying those objects)
    Confirm: Stops processing before any changes are made to an object.

    10. !: Avoid empty Catch block

    11. !: Use Set-StrictMode in your dev scripts

    Set-StrictMode -Version Latest

    21. !: Use #Requires statement

    #Requires -Version 3.0   
#Requires -Modules ActiveDirectory, DnsClient  
#Requires -RunAsAdministrator

where

B -- inherited from common practices
T -- like Taylor rules for Linux
! -- Important

  1. https://devblogs.microsoft.com/scripting/use-powershell-to-easily-convert-decimal-to-binary-and-back/

  2. https://stackoverflow.com/questions/29119383/powershell-use-regular-expression-to-split-a-string

  3. https://adamtheautomator.com/a-simpler-ifthen-conditional-logic-in-powershell/

  4. https://www.ntu.edu.sg/home/ehchua/programming/howto/Regexe.html
    https://www.regular-expressions.info/floatingpoint.html

  5. https://stackoverflow.com/questions/885349/how-do-i-write-a-powershell-script-that-accepts-pipeline-input

  6. https://stackoverflow.com/questions/885349/how-do-i-write-a-powershell-script-that-accepts-pipeline-input

  7. http://powershell-guru.com/powershell-best-practice-2-use-named-parameters-not-positional-and-partial-parameters/

  8. https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/select-string?view=powershell-6

  9. https://stackoverflow.com/questions/53867147/grep-and-sed-equivalent-in-powershell

  10. https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/out-file?view=powershell-6

  11. https://devblogs.microsoft.com/scripting/powertip-use-powershell-to-check-string-for-a-match/

  12. https://stackoverflow.com/questions/33511772/read-file-line-by-line-in-powershell

  13. https://stackoverflow.com/questions/5592531/how-to-pass-an-argument-to-a-powershell-script

  14. https://stackoverflow.com/questions/7976646/powershell-store-entire-text-file-contents-in-variable

  15. https://stackoverflow.com/questions/19122755/output-echo-a-variable-to-a-text-file

  16. https://powershell.org/forums/topic/how-to-use-ansi-vt100-formatting-in-powershell-ooh-pretty-colors/

ANNEX A. POWERSHELL BEST PRACTICES

!  #1: Use full cmdlet name in scripts (not alias)  
       Get-Command -CommandType Alias ~300      
         % -> ForEach-Object  
         ? -> Where-Object  
B  #2: Use named parameter in scripts   
       (not positional and partial parameter)  
T  #3: Avoid Write-Host  
   #4: Use CIM cmdlet (not WMI cmdlet)  
B  #5: Avoid excessive comments (over-commenting)  
   #6: Use singular noun for cmdlet (not plural noun, boat -- boats)  
   #7: Use approved verb   
       (not unapproved verb, Get-Verb vs all other verbs)  
!  #8: Use WhatIf and Confirm parameters  
       WhatIf : Only displays the objects that would be affected   
                and what changes would be made to those objects   
                (without the worry of modifying those objects)  
       Confirm: Stops processing before any changes are made   
                to an object.  
B  #9: It is recommended to use region statement to split your code   
      into logical parts in your scripts.  
! #10: Avoid empty Catch block  
! #11: Use Set-StrictMode in your dev scripts  
       Set-StrictMode -Version Latest  
  #12: Avoid Out-Null cmdlet  
  #13: Avoid doublequotes in strings if not necessary   
       (Use proper quotes: 'strict' or "weak")  
  #14: Specify the extension for applications  
  #15: Execute scripts with -NoProfile parameter  
  #16: Update the help  
  #17: Use the same parameter name than the native one  
  #18: Don’t use Notepad as a script editor (use PS ISE or VS Code)  
  #19: Check parameters with PSBoundParameters  
  #20: Use full key name for calculated properties  
! #21: Use #Requires statement  
         #Requires -Version 3.0   
         #Requires -Modules ActiveDirectory, DnsClient  
         #Requires -RunAsAdministrator  
  #22: Use Obsolete attribute for backwards compatibility  
B #23: Avoid the horizontal scrolling (too long one-liners commands)*

That's it.

*) http://powershell-guru.com/powershell-best-practice-23-avoid-the-horizontal-scrolling-too-long-one-liners-commands/

ANNEX B. Get-Verb

PS D:\TMP\Ps> Get-Verb | Measure-Object  

Count    : 98  
Average  :  
Sum      :  
Maximum  :  
Minimum  :  
Property :  

PS D:\TMP\Ps> Get-Verb  

Verb        Group  
----        -----  
Add         Common  
Clear       Common  
Close       Common  
Copy        Common  
Enter       Common  
Exit        Common  
Find        Common  
Format      Common  
Get         Common  
Hide        Common  
Join        Common  
Lock        Common  
Move        Common  
New         Common  
Open        Common  
Optimize    Common  
Pop         Common  
Push        Common  
Redo        Common  
Remove      Common  
Rename      Common  
Reset       Common  
Resize      Common  
Search      Common  
Select      Common  
Set         Common  
Show        Common  
Skip        Common  
Split       Common  
Step        Common  
Switch      Common  
Undo        Common  
Unlock      Common  
Watch       Common  
Backup      Data  
Checkpoint  Data  
Compare     Data  
Compress    Data  
Convert     Data  
ConvertFrom Data  
ConvertTo   Data  
Dismount    Data  
Edit        Data  
Expand      Data  
Export      Data  
Group       Data  
Import      Data  
Initialize  Data  
Limit       Data  
Merge       Data  
Mount       Data  
Out         Data  
Publish     Data  
Restore     Data  
Save        Data  
Sync        Data  
Unpublish   Data  
Update      Data  
Approve     Lifecycle  
Assert      Lifecycle  
Complete    Lifecycle  
Confirm     Lifecycle  
Deny        Lifecycle  
Disable     Lifecycle  
Enable      Lifecycle  
Install     Lifecycle  
Invoke      Lifecycle  
Register    Lifecycle  
Request     Lifecycle  
Restart     Lifecycle  
Resume      Lifecycle  
Start       Lifecycle  
Stop        Lifecycle  
Submit      Lifecycle  
Suspend     Lifecycle  
Uninstall   Lifecycle  
Unregister  Lifecycle  
Wait        Lifecycle  
Debug       Diagnostic  
Measure     Diagnostic  
Ping        Diagnostic  
Repair      Diagnostic  
Resolve     Diagnostic  
Test        Diagnostic  
Trace       Diagnostic  
Connect     Communications  
Disconnect  Communications  
Read        Communications  
Receive     Communications  
Send        Communications  
Write       Communications  
Block       Security  
Grant       Security  
Protect     Security  
Revoke      Security  
Unblock     Security  
Unprotect   Security  
Use         Other

TASKBOOK

==========

Solve in Powershell:

  1. PRINT BINARY NUMBERS WITH LEADING ZEROES, LIKE SO:

    0  00   
1  01  
2  10   
3  11  
..

    awk solution

    # awk -f 1.awk  
BEGIN {  
  N=3; # number of bits  
  n=1; a[0]="";  
  for(i=0;i<3;i++) {  
    for(j=0;j<n;j++) {   
      a[n+j]="1"a[j];   
      a[j]="0"a[j];   
    }  
    n+=j;  
  }  
  for(i=0;i<n;i++)   
    print i," ", a[i];  
}

  2. PRINT BINARY NUMBERS WITH LEADING ZEROES, LIKE SO:

    00 01 10 11

    awk solution

    # awk -f 2.awk  
BEGIN {  
  ORS=" "; # the output record separator  
  N=3;     # number of bits  
  n=1; a[0]="";  
  for(i=0;i<3;i++) {  
    for(j=0;j<n;j++) {   
      a[n+j]="1"a[j];   
      a[j]="0"a[j];   
    }  
    n+=j;  
  }  
  for(i=0;i<n;i++)   
    print a[i];  
  ORS="\n"; print;  
}

  3. PRINT TRUTH TABLE FOR NOT, OR, XOR, AND

    # gawk -f 3.awk  
BEGIN {  
  n=1; a[0]="";  
  for(i=0;i<2;i++) {  
    for(j=0;j<n;j++) {  
      a[n+j]="1"a[j];  
      a[j]="0"a[j];  
    }  
    n+=j;  
  }  
  print "n","ab","!a","!b","OR","XOR","AND"  
  for(i=0;i<n;i++)  
    print i, a[i], "",  
    xor(rshift(and(i,2),1),1), "",  
    xor(and(i,1),1), "",  
    or(and(i,1),rshift(and(i,2),1)), "",  
    xor(and(i,1),rshift(and(i,2),1)), "",  
    and(and(i,1),rshift(and(i,2),1));  
}  

    $ gawk -f 2.awk  
n ab !a !b OR XOR AND  
0 00  1  1  0  0  0  
1 01  1  0  1  1  0  
2 10  0  1  1  1  0  
3 11  0  0  1  0  1

  4. PRINT CYRILLIC ALPHABET

    # awk -f 4.awk  
function chr(c) {  
  return sprintf("%c",c+0)  
}  
  
BEGIN {  
  ORS=""  
  for (x=0x410;x<=0x44f;x++) {  
    if(x==0x430) print "\n";  
    print chr(x);  
  }  
  ORS="\n"; print;  
}  

    АБВГДЕЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ  
абвгдежзийклмнопрстуфхцчшщъыьэюя

  5. ALFRED VAIL'S CODE (MORSE CODE)

    # awk -f 5.awk  
BEGIN {  
  si="ABCDEFGHIJKLMNOPQRSTUVWXYZ ";  
  s=".-:-...:-.-.:-..:.:..-.:--.:....:..:.---:-.-:";  
  s=s".-..:--:-.:---:.--.:--.-:.-.:...:-:..-:...-:";  
  s=s".--:-..-:-.--:--..: ";  
  split(si,idx,"");  
  split(s,cipher,":");  
  for(i in idx) ci[idx[i]]=i;  
  splain="HELLO WORLD";  
  split(splain,plain,"");  
  for(i in plain) printf("%s ", cipher[ci[plain[i]]]);  
  print;  
}

  6. SIMPLE CALCULATOR

    # echo 2 + 3 | awk -f 6.awk  
{  
  z=0;  
  switch ($2) {  
    case "+" : z=$1+$3; break;  
    case "-" : z=$1-$3; break;  
    case "*" : z=$1*$3; break;  
    case "/" : z=$1/$3; break;  
    case "%" : z=$1%$3; break;  
    default  : print "Illegal Operation",$2;  
  }  
  print $0," : ",$1,$2,$3,"=",z;  
}

  7. MULTIPLICATION TABLE FOR BASE 10

    # echo 10 | awk -f 7.awk  
{  
  printf("  :");   
  for(y=1;y<=$1-1;y++)   
    printf("  %d",y);   
  printf("\n");  
  printf("...");   
  for(y=1;y<=$1-1;y++)   
    printf(" ..");   
  printf("\n");  
  for(x=1;x<=$1-1;x++) {  
    printf("%d : ",x);  
    for(y=1;y<=$1-1;y++)   
      printf("%02d ",x*y);   
    printf("\n");  
  }  
}  

    $ echo 10 | awk -f 7.awk  
  :  1  2  3  4  5  6  7  8  9  
... .. .. .. .. .. .. .. .. ..  
1 : 01 02 03 04 05 06 07 08 09  
2 : 02 04 06 08 10 12 14 16 18  
3 : 03 06 09 12 15 18 21 24 27  
4 : 04 08 12 16 20 24 28 32 36  
5 : 05 10 15 20 25 30 35 40 45  
6 : 06 12 18 24 30 36 42 48 54  
7 : 07 14 21 28 35 42 49 56 63  
8 : 08 16 24 32 40 48 56 64 72  
9 : 09 18 27 36 45 54 63 72 81

  8. DELAY INTRODUCED

    # echo 1010 1101 | awk -f this.awk  
  
BEGIN {  
  print $1;  
  system("sleep 1.2");  
  print $2;  
}

  9. VALIDATE BOOLEAN

    # echo false | awk -f 9.awk  
{  
  x=$0;  
  x=x=="true"?1:x; x=x=="false"?0:x;  
  print x~/^(0|1)$/?"Ok":"NaB",x  
}

  10. VALIDATE INTEGER

    # echo -1074 | awk -f 10.awk  
{  
  print $0 ~ /^([+-]?[1-9][0-9]*|0)$/ ? "Ok" : "NaN",$0  
}

  11. VALIDATE REAL

    # echo +1.074e-3 | awk -f 10.awk  
{  
  print $0~/^([-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?)$/?"Ok":"NaN",$0  
}

  12. MORSE AND BACK. UNIX STYLE

$ cat lookup  
A  .-  
B  -...  
C  -.-.  
D  -..  
E  .  
F  ..-.  
G  --.  
H  ....  
I  ..  
J  .---  
K  -.-  
L  .-..  
M  --  
N  -.  
O  ---  
P  .--.  
Q  --.-  
R  .-.  
S  ...  
T  -  
U  ..-  
V  ...-  
W  .--  
X  -..-  
Y  -.--  
Z  --..  
0  -----  
1  .----  
2  ..---  
3  ...--  
4  ....-  
5  .....  
6  -....  
7  --...  
8  ---..  
9  ----.  
  
$ cat lookup | awk '{print $2"\t"$1}' > rlookup  
  
$ cat wrd  
K  
O  
H  
U  
K  
E  
  
$ awk 'NR==FNR{a[$1]=$2;next} $1 in a {print a[$1]}' \  
  lookup wrd > rwrd  
  
$ cat rwrd  
-.-  
---  
....  
..-  
-.-  
.  
  
$ awk 'NR==FNR{a[$1]=$2;next} $1 in a {print a[$1]}' \  
  rlookup rwrd  
K  
O  
H  
U  
K  
E

  1. https://stackoverflow.com/questions/9351902/how-can-i-get-the-length-of-an-array-in-awk

  2. https://stackoverflow.com/questions/9351902/how-can-i-get-the-length-of-an-array-in-awk?noredirect=1&lq=1

    The way you introduce local variables in awk is as extra function parameters and the convention is to indicate this by adding extra spaces before these parameters.

  3. ORS -- The output record separator, by default a newline.

    https://stackoverflow.com/questions/24331687/is-it-possible-to-print-the-awk-output-in-the-same-line

  4. ord() and chr() in awk

    https://www.gnu.org/software/gawk/manual/html_node/Ordinal-Functions.html

  5. Initialize array in awk

    https://stackoverflow.com/questions/14063783/how-to-initialize-an-array-of-arrays-in-awk

  6. Use printf instead of print

    https://stackoverflow.com/questions/2021982/awk-without-printing-newline

  7. Basic idea for example 6

    https://www.unix.com/shell-programming-and-scripting/60653-search-replace-string-file1-string-lookup-table-file2.html

  8. Script explained step by step

https://stackoverflow.com/questions/32481877/what-are-nr-and-fnr-and-what-does-nr-fnr-imply