Code – My homepage and Blog

On this page you will find four sections:

Kotlin (example code)
Using curl (db access)
Bash-shell script
Updated C-standard

I have some Kotlin code examples. For those of you who have bought my book “The Linux Book”, I have updated the menu based on bash-shell. In the book “Linux server- og utviklingsmiljø” I have also updated “C-standard”. You will see this in the last section of this page.

Kotlin

Many times, we need to access REST/API-solution in Kotlin we can use Java 11 HttpClient for easy access. I have some code below which shows this.

You can use HTTP get request in sync mode or in Async mode. In all my examples below I use sync mode.

In my first example, I access REST/API-soltion with POST and I get messages. In the code, we check how much time the system is using for reading the data.

import java.net.URI
import java.net.http.HttpClient
import java.net.http.HttpRequest
import java.net.http.HttpResponse
import java.time.Duration
import kotlin.system.measureNanoTime
import kotlin.system.measureTimeMillis
import kotlin.time.measureTime
fun main(args: Array<String>) {
httpGetRequestSync()
}
fun printBorder(border: String, timesToRepeat: Int) {
repeat(timesToRepeat) {
print(border)
}
println()
}
fun httpGetRequestSync() {
val httpClient: HttpClient = HttpClient.newBuilder()
.connectTimeout(Duration.ofSeconds(10))
.build()
// val SAML_TOKEN =”XXXX”
val SAML_TOKEN = System.getenv(“SAML_TOKEN”)
// neste linje kan fjernes
val elapsed = measureTimeMillis {
val start_part: Int = 105100
val slutt_part: Int = 105102
// fun sum(start_part: Int, slutt_part: Int): Int {
// return slutt_part – start_part
// }
val diff = slutt_part – start_part
// println(“Antall parter $diff”)
for (partsnummer in start_part..slutt_part) {
val elapsed_per = measureTimeMillis {
val border = “-“
val timesToRepeat = 150
printBorder(border, timesToRepeat)
val requestHead = HttpRequest.newBuilder()
.GET()
.uri(URI.create(“http://databoks-miljo.no/api/meldinger?partsnummer=${partsnummer}&spraak=nb_NO&hentAktive=true”))
.header(“Authorization”, “SAML/GZ ” + SAML_TOKEN)
.header(“Content-Type”, “application/json”)
.header(“Accept”, “application/json”)
.header(“Klientid”, “curl”)
.header(“Korrelasjonsid”, “korrelasjon”)
.build()
val httpResponse = httpClient.send(requestHead, HttpResponse.BodyHandlers.ofString())
println(“httpResponse statusCode = ${httpResponse.statusCode()}”)
println(httpResponse.body())
}
println(“Måler tiden totalt i antall milliskunder ${elapsed_per}”)
}
val border = “=”
val timesToRepeat = 150
printBorder(border, timesToRepeat)
println(“Antall parter $diff”)
}
// 2 neste linjene kan fjernes
val border = “=”
val timesToRepeat = 150
printBorder(border, timesToRepeat)
val sekunder: Double = elapsed / 1000.0
println(“Måler tiden totalt i antall sekunder ${sekunder}”)
}

In this section I have som example code in Kotlin

Please check the Kotlin links.

New to Kotlin, check out the links below.

Example with bash and curl instead of kotlin program for acessing a REST-interface.

Using curl (db access)

$ more adduser.sh

#!/bin/bash
i=101000
while [ $i -ne 102000 ]
do
i=$(($i+1))
echo “$i”
curl -v -X POST “$DATABOX_HOST/api/meldinger/publiser/$i” -d ‘{ “id_melding”: 2, “domene”: “innkreving”, “kategori”: “kat” }’ –header “Authorization: SAML/GZ $SAML_TOKEN” –header ‘Content-Type: application/json’ –header ‘Accept: app
lication/json’ –header ‘Klientid: curl’ –header ‘Korrelasjonsid: korrelasjon’ –header ‘Meldingsid: mid’
done

Clean start

sudo apt install maven
git clone https://github.com/tax/openshift-reference-springboot-server.git
openshift-reference-springboot-server/
mvn clean install
cd targetgit
java -jar openshift-reference-springboot-server-2.0-SNAPSHOT.jar

Bash-script

Below you find an updated global bash script (menu) from my book “The Linux Book”.

#!/bin/bash
clear
while test “$answer” != “0”
do
clear
echo “”
echo ” 1 – List files(directory) “
echo ” 2 – Change catalog “
echo ” 3 – File check “
echo ” 4 – Copy file “
echo ” 5 – Remove file “
echo ” 6 – Change filename “
echo ” 7 – Output file to screen “
echo ” 8 – Output file to printer”
echo ” 9 – Users logged in to the computer”
echo ” 10 – Who am i”
echo ” 11 – Current directory”
echo ” 12 – Make a directory”
echo ” 13 – Delete empty directory”
echo ” 14 – Quit the menu”
echo “”
echo -n ” Choose a function (1/../14) and press <RETURN> key :”
read answer
cd $home
#
# 1 – List files(directory)
#
if test “$answer” = “1”;then
clear
echo “”
echo “Current/working directory is :”
pwd
echo “”
echo “List files and directories”
ls -la | more
echo “”
echo -n “Press <RETURN> to continue :”
read stop
fi
#
# 2 – Change directory
#
if test “$answer” = “2”;then
clear
echo “”
echo -n “Current/working directory :”
pwd
echo “”
echo “To continue in current/working directory answer with
‘.'(period) and press <RETURN>”
echo “If you want to move one level up, answer with
‘..'(two periods) and press <RETURN>”
echo “”
echo “If you want to move back to your own home-directory you only need to press <RETURN>”
echo “”
echo “If you want to move to a child-directory just write the name of the directory and press <RETURN>”
echo “”
echo -n “Which directory would you like to use :”
read dir
cd $dir
echo “”
echo -n “New active directory is :”
pwd
echo “”
echo -n “Press <RETURN> to continue :”
read stop
fi
#
# 3 – File check
#
if test “$answer” = “3”;then
clear
echo “”
echo -n “Which file do you wish to check :”
read file
if test -d “$file”;then
echo “”
echo ” “$file” is a directory”
echo “”
echo -n “Press <RETURN> to continue :”
read stop
fi
if test -r “$file”;then
echo “”
echo “We can read the file”
fi
if test -w “$file”;then
echo “”
echo “We can write to the file”
fi
if test ! -f “$file”;then
echo “”
echo “”$file” is not a sub-directory or a file in the specified directory”
fi
echo “”
echo -n “Press <RETURN> to continue :”
read stop
fi
#
# 4 – Copy file
#
if test “$answer” = “4”;then
clear
echo “”
echo “”
echo -n “You are now placed in directory :”
pwd
echo “”
echo -n “Which file do you want to copy :”
read fromfile
echo “”
if test -s “$fromfile”;then
echo -n “Which directory/file would you like to copy to :”
read tofile
if test ! -s “$tofile”;then
cp “$fromfile” “$tofile”
else
echo “”
echo -n “”$tofile” exist do you want overwrite (y/n) :”
read yes
if test “$yes” = “y”;then
cp “$fromfile” “$tofile”
fi
fi
else
echo “”
echo -n “”$fromfile” do not exist – press <RETURN> :”
read stop
fi
fi
#
# 5 – Delete file
#
if test “$answer” = “5”;then
clear
echo “”
echo -n “Which file do you want to delete :”
read file
if test -f “$file”;then
clear
echo “”
echo -n “”$file” exists. Do you really want to delete the file (y/n) :”
read yes
if test “$yes” = “y”;then
rm $file
fi
else echo “”
echo -n “”$file” do not exists – press <RETURN>”
read stop
fi
fi
#
# 6 – Change name on file
#
if test “$answer” = “6”;then
clear
echo “”
echo -n “You are now in directory :”
pwd
echo “”
echo -n “Which filename would you like to change :”
read file
if test -f “$file”;then
clear
echo “”
echo -n “”$file” exists. Please give a new name :”
read newname
if test ! -f “$newname”;then
mv “$file” “$newname”
else
echo “”
echo -n “”$newname” exists – press <RETURN> :”
read stop
fi
else
echo “”
echo -n “”$file” do not exists – press <RETURN> :”
read stop
fi
fi
#
# 7 – Output file to monitor screen
#
if test “$answer” = “7”;then
clear
echo “”
echo “If the file is more than one page you may continue by pressing the <RETURN> key”
echo “”
echo -n “Which file would you like to see on your monitor screen :”
read file
if test -s “$file”;then
more “$file”
echo “”
echo -n “Press <RETURN> to continue :”
read stop
else
echo “”
echo “The file do not exists or is empty”
echo “”
echo -n “Press <RETURN> to continue :”
read stop
fi
fi
#
# 8 – Output file to printer
#
if test “$answer” = “8”;then
clear
echo “”
echo -n “Which file would you like to print :”
read file
echo “”
lpr $file
echo “”
fi
#
# 9 – Users logged on the system
#
if test “$answer” = “9”;then
clear
echo “”
echo -n “Please, wait…..”
who > /tmp/who-list
clear
echo “”
echo “Active users logged on the system :”
echo “”
cat /tmp/who-list
echo “”
echo -n “Number of users logged on the system :”
cat /tmp/who-list | wc -l
echo “”
echo -n “Press <RETURN> to continue:”
read stop
fi
#
# 10 – Who am I
#
if test “$answer” = “10”;then
clear
echo “”
echo -n “I am user :”
whoami
echo “”
echo -n “Press <RETURN> to continue :”
read stop
fi
#
# 11 – Current directory
#
if test “$answer” = “11”;then
clear
echo “”
echo -n “Current directory is :”
pwd
echo “”
echo -n “Press <RETURN> to continue :”
read stop
fi
#
# 12 – Make a directory
#
if test “$answer” = “12”;then
clear
echo “”
echo -n “Current directory is :”
pwd
echo ” “
echo -n “Is this the right directory – would you like to continue (y/n) :”
read yes
if test “$yes” = “y”;then
echo “”
echo -n “What is the name of the new sub-directory :”
read subdir
if test ! -d “$subdir”;then
mkdir “$subdir”
if test ! -d “$subdir”;then
echo “”
echo -n “”$subdir” this directory do not exists :”
read stop
fi
else
echo “”
echo -n “”$subdir” this directory do already exists – press <RETURN> :”
read stop
fi
fi
fi
#
# 13 – Delete empty directory
#
if test “$answer” = “13”;then
clear
echo “”
echo -n “Current directory is :”
pwd
echo “”
echo -n “Which empty directory would you like to delete :”
read file
if test -d “$file”;then
cd $file
echo “”
echo “Checking directory”
ls -la
cd ..
echo “”
echo -n “Any files in that directory? – (y/n) :”
read yes
if test “$yes” = “y”;then
rmdir “$file”
if test ! -d “$file”;then
echo “”
echo -n “”$file” is deleted – press <RETURN> :”
read stop
fi
fi
else
echo “”
echo -n “”$file” is not a directory – press <RETURN> :”
read stop
fi
fi
#
# 14 – Quit the menu
#
if test “$answer” = “14”;then
exit;
fi
done

C

Updated C-standard from my book “Linux server- og utviklingsmiljø”.

C client-programs and C-functions should be written using Hungarian Standard. Hungarian Standard is a naming standard for variables, where the first one to three characters represents the datatype, and the name of the variable follows with initial caps for each word (ex. usHoldLimit).
Use Hungarian Standard when declaring variables
Use the formatted-text boxes in the example below to mark start of program and start of each function
Write extended comments within the functions using ‘/*’ and ‘*/’
Use 4 blanks as indent, no TABs
ANSI-standard, with functions prototype at top and paramters declared within the pharntesis of each function
Variable-names should be declared starting in column 32.
Let start- and end-of-loop signs (‘{‘ and ‘}’) be on seperate lines
If a seperate client-program, let the main-function be the first function
When accessing other programs within C-programs, do NOT use malloc() and free(), instead, use mi_alloc() and mi_free()
Type Description
Int iInteger
unsigned int uiInteger
Short siShort
unsigned short usShort
Float fNumber
Char cByte
Char sString
int * piPointer
unsigned int * uiInteger
short * psiShort
unsigned short * pusShort
float * pfFloat
char * psPointer
Boolean bExist
image pointer * pimImage
void vVoid
void * pvVoid
struct stStruct
struct * pstStruct
char * apsArray[190];
[david@nittedal david]$ cat c-mal.c
/*
+————————————————–+
| Program name : |
| Author : |
| Last changed : |
| Description : |
| |
+————————————————–+
*/
/* Include files */
/* Define’s */
/* Prototypes */
/*
+————————————————–+
| Function : |
| Description: |
| |
| |
| |
+————————————————–+
*/
Example:
/*
+—————————————————+
| Program name : sPrepPar.c |
| Author : David Elboth |
| Last changed : 6/8-2004 |
| _____________________________ ____ |
| Description: |
| |
| Receives a text-string as the only |
| parameter and changes all ‘ ‘ to ‘+’. |
| |
+—————————————————+
*/
/* Include files */
#include <mi.h>
/* Define’s */
#define PLUS_SIGN ‘+’
#define BLANK_SIGN ‘ ‘
#define END_STRING ‘\0’
/* Prototypes */
mi_text *_PrepPar (mi_text *psPar);
/*
+———————————————————–+
| Function : _PrepPar |
| Description: Converts the input string psPar to a regular |
| character-pointer. Scans to the string and substitutes |
| blanks to |
| ‘+’. If the string contains leading blanks, these are |
| removed. |
+———————————————————–+
*/
mi_text *_PrepPar (mi_text *psPar)
{
char *psPlusWord;
char *psHead;
psPlusWord = mi_text_to_string (psPar);
/* Remove initial blanks */
for (; *psPlusWord == BLANK_SIGN; psPlusWord++) {}
psHead = psPlusWord;
while (*psPlusWord != END_STRING)
{
if (*psPlusWord == BLANK_SIGN)
{
*psPlusWord = PLUS_SIGN;
}
psPlusWord++;
}
/* Move pointer to first byte */
psPlusWord = psHead;
/* Convert the charcter-pointer to Illustra-text */
psPar = mi_string_to_text (psPlusWord);
/* Return the converted string to caller-function */
return (psPar);
}