LOYOLITE

How do we kill the processes in linux/unix with a process name?

noreply@blogger.com (Rajakrishna Reddy) — Sat, 12 Nov 2022 08:23:00 +0000

Below is the command to kill all the processes running based on a process name: ps -ef | grep {process_name} | grep -v grep | awk '{print $2}' | xargs kill

Eg: Kill all the processes that have chrome as part of the process name: ps -ef | grep chrome | grep -v grep | awk '{print $2}' | xargs kill

Calculate Network Subnet Range efficiently!

noreply@blogger.com (Rajakrishna Reddy) — Mon, 09 Mar 2020 07:18:00 +0000

import lombok.AccessLevel;
import lombok.Builder;
import lombok.Data;
import lombok.experimental.Accessors;

import java.util.List;
import java.util.regex.Pattern;
import java.util.stream.IntStream;

import static com.varra.auth.utils.CommonUtils.ipStringToLong;
import static java.lang.Integer.parseInt;
import static java.lang.Math.pow;
import static java.util.stream.Collectors.toList;

/**
 * TODO Description go here.
 *
 * @author Rajakrishna V. Reddy
 * @version 1.0
 */
public class SubnetCalculator {

    private static final Pattern CIDR_PATTERN = Pattern.compile("/");

    @Accessors(chain = true, fluent = true)
    @Data
    @Builder(access = AccessLevel.PRIVATE)
    public static class Subnet {
        private final int cidr;
        private final int ipCount;
        private final int startIp;
        private final int endIp;

        public static Subnet of(final String ipWithCIDR)
        {
            final String[] ipWithCIDRTokens = CIDR_PATTERN.split(ipWithCIDR);
            final int numericCIDR = parseInt(ipWithCIDRTokens[1]);
            final int netmaskNumeric = 0xffffffff << (32 - numericCIDR);
            final int numberOfIPs = (int) pow(2, 32 - numericCIDR) - 1;
            final int baseIP = (int)ipStringToLong(ipWithCIDRTokens[0]) & netmaskNumeric;
            return Subnet.builder().cidr(numericCIDR).ipCount(numberOfIPs).startIp(baseIP).endIp(baseIP + numberOfIPs -1).build();
        }
    }

    /**
     * Specify IP in CIDR format like: new IPv4("10.1.0.25/16");
     *
     * @param ipWithCIDR ""
     */
    public static List<String> getAvailableIps(final String ipWithCIDR) throws NumberFormatException {
        return getAvailableIpsAsIntegers(ipWithCIDR).mapToObj(CommonUtils::ipLongToString).collect(toList());
    }

    /**
     * Specify IP in CIDR format like: new IPv4("10.1.0.25/16");
     *
     * @param ipWithCIDR ""
     * @return IntStream Stream of ips as integers
     */
    public static IntStream getAvailableIpsAsIntegers(final String ipWithCIDR) throws NumberFormatException {
        final Subnet subnet = Subnet.of(ipWithCIDR);
        return IntStream.range(1, subnet.ipCount()).map(i -> i + subnet.startIp());
    }

    public static boolean isIpWithInSubnet(final String ipWithCIDR, final String ip) throws NumberFormatException {
        final Subnet subnet = Subnet.of(ipWithCIDR);
        final int ipAsInt = (int) ipStringToLong(ip);
        return subnet.startIp() <= ipAsInt && ipAsInt <= subnet.endIp();
    }
}

Problem with github: permission denied to your own repo In Windows!! ??

noreply@blogger.com (Rajakrishna Reddy) — Fri, 07 Feb 2020 09:42:00 +0000

Using multiple GitHub Accounts on Windows sucks by default. If you are tired of Window's Credential Manager storing only one account's credential for git:https://github.com then here is a 1-minute fix for you.

TL;DR

If you know what you're doing just:

delete your GitHub credentials from Windows Credential Manager
run git config --global credential.github.com.useHttpPath true
continue coding

If you need more detailed instructions and learn about the background just read on here: https://dev.to/configcat/lazy-man-s-guide-multiple-github-https-accounts-on-windows-2mad

Lazy man's guide: multiple GitHub HTTPS accounts on Windows - DEV Community

Git is definitely one of those things that gets painful on Windows. Especially if you're using some GUI client as well. Not sure how I feel about using SSH config vs git config to select the right key, but I've mostly phased out HTTPS because of the headaches (other than for the occasional quick clone).

dev.to

Problem with github: permission denied to your own repo?

noreply@blogger.com (Rajakrishna Reddy) — Thu, 05 Dec 2019 09:57:00 +0000

I had this problem too but managed to solve it, the error is that ur computer has saved a git username and password so if you shift to another account the error 403 will appear. Below is the solution

For Windows you can find the keys here:

control panel > user accounts > credential manager > Windows credentials > Generic credentials

Next -> remove the Github keys.

How to replace all the entries in a string in Javascript? like replaceAll?

noreply@blogger.com (Rajakrishna Reddy) — Tue, 13 Aug 2019 06:38:00 +0000

This should do the trick by adding a new method (replaceAll) to the String prototype.

String.prototype.replaceAll = function(search, replacement){

return this.replace(new RegExp(search, 'g'), replacement);

};

How to increase the number of processes in Oracle DB

noreply@blogger.com (Rajakrishna Reddy) — Tue, 07 Aug 2018 09:16:00 +0000

The solution to this question is to increase the number of processes :

Open command prompt
sqlplus / as sysdba
startup force;
show parameter processes; -- This shows 150 processes allocated, i will increase the count to 800 now
alter system set processes=800 scope=spfile;

Tried and tested.

How to setup a beyond compare as git mergetool?

noreply@blogger.com (Rajakrishna Reddy) — Mon, 02 Jul 2018 11:55:00 +0000

How to set up a beyond compare as git mergetool?

git config --global diff.tool bc3

git config --global difftool.bc3.path "c:/program files/beyond compare 4/bcomp.exe"

git config --global merge.tool bc3

git config --global mergetool.bc3.path "c:/program files/beyond compare 4/bcomp.exe"

If the above instructions aren't working on your system, it's possible repository local settings are overriding the global settings.

The contents of the global git config file (c:\users\username\.gitconfig) from my working test system:

[diff]

tool = bc3

[difftool "bc3"]

path = c:/program files/beyond compare 4/bcomp.exe

[merge]

tool = bc3

[mergetool "bc3"]

path = c:/program files/beyond compare 4/bcomp.exe

How to merge a branch in git

noreply@blogger.com (Rajakrishna Reddy) — Mon, 28 May 2018 08:54:00 +0000

Follow the commands below to do the auto merge the branch in git:

$ git checkout -b {new-branch-name}

$ git merge --no-ff {old-branch-name}

$ git push -u origin {new-branch-name}

Concatenating and combining lists in Python

noreply@blogger.com (Rajakrishna Reddy) — Fri, 25 May 2018 20:17:00 +0000

CODE:

[4, None, 'foo'] + [7, 8, (2, 3)]

x = [4, None, 'foo']

x.extend([7, 8, (2, 3)])

print(x)

OUTPUT:

[4, None, 'foo', 7, 8, (2, 3)]

Ternary expressions in Python

noreply@blogger.com (Rajakrishna Reddy) — Fri, 25 May 2018 20:03:00 +0000

A ternary expression in Python allows you to combine an if-else block that produces

a value into a single line or expression. The syntax for this in Python is:

value = true-expr if condition else false-expr

Here, true-expr and false-expr can be any Python expressions. It has the identical

effect as the more verbose:

if condition:

value = true-expr

else:

value = false-expr

This is a more concrete example:

CODE:

x = 5

'Non-negative' if x >= 0 else 'Negative'

OUTPUT:

'Non-negative'

What is pass in Python

noreply@blogger.com (Rajakrishna Reddy) — Fri, 25 May 2018 20:00:00 +0000

pass is the "no-op" statement in Python. It can be used in blocks where no action is to

be taken (or as a placeholder for code not yet implemented); it is only required

because Python uses whitespace to delimit blocks:

Eg:

if x < 0:

print('negative!')

elif x == 0:

# TODO: put something smart here

pass

else:

print('positive!')

How to chain comparisons in Python

noreply@blogger.com (Rajakrishna Reddy) — Fri, 25 May 2018 19:57:00 +0000

CODE:

print(4 > 3 > 2 > 1)

OUTPUT:

True

What are the datetime format specifications (ISO C89 compatible) in Python

noreply@blogger.com (Rajakrishna Reddy) — Fri, 25 May 2018 19:52:00 +0000

Below are the Datetime format specification (ISO C89 compatible) in Python:

Why triple quotes (" " ") are used in Python

noreply@blogger.com (Rajakrishna Reddy) — Fri, 25 May 2018 19:47:00 +0000

For multiline strings with line breaks, you can use triple quotes, either ''' or " " ":

c = """

This is a long string that

spans multiple lines

"""

Standard Python scalar types

noreply@blogger.com (Rajakrishna Reddy) — Fri, 25 May 2018 19:45:00 +0000

Below are the standard Python scalar types:

Type: Description

None: The Python "null" value (only one instance of the None object exists)

str: String type; holds Unicode (UTF-8 encoded) strings

bytes: Raw ASCII bytes (or Unicode encoded as bytes)

float: Double-precision (64-bit) floating-point number (note there is no separate double type)

bool: A True or False value

int: Arbitrary precision signed integer

How to check/get/set an attribute or a method in Python (Reflection)

noreply@blogger.com (Rajakrishna Reddy) — Fri, 25 May 2018 19:33:00 +0000

Python allows an easy way to check whether an object contains/has an attribute or method with the specified name as follows:

1) getattr:

Gets the attribute/method with the specified name, usage as follows:

usage: getattr(obj, 'method/attribute name')

eg:

a='RK';

getattr(a, 'split')

2) hasattr:

Checks whether object has the attribute/method with the specified name, usage as follows:

usage: hasattr(obj, 'method/attribute name')
eg:
a='RK';
hasattr(a, 'split')

3) setattr:

Sets the attribute/method with the specified name, usage as follows:

usage: setattr(obj, 'method/attribute name', value)

eg:

a=Employee(23)

setattr(a, 'id', 45)

Python assignments are by references

noreply@blogger.com (Rajakrishna Reddy) — Fri, 25 May 2018 19:22:00 +0000

When assigning a variable (or name) in Python, you are creating a reference, have a look at below:

CODE:

a=[1,2]

b=a

print("Before append: ", b)

b.append(3)

print("Shows a & b are same references, after append to b, a: ", a)

OUTPUT:

Before append:  [1, 2]

Shows a & b are same references, after append to b, a:  [1, 2, 3]

How to get rid of `grep: warning: GREP_OPTIONS is deprecated; please use an alias or script`?

noreply@blogger.com (Rajakrishna Reddy) — Fri, 25 May 2018 19:09:00 +0000

Need to have an alias for grep to make the output colored as follows and unset the GREP_OPTIONS.

alias grep="grep --color=auto"
unset GREP_OPTIONS

How to create a self signed certificate, and how to validate the JWT token using Nimbus

noreply@blogger.com (Rajakrishna Reddy) — Mon, 21 May 2018 09:15:00 +0000

This post will help you to generate a self-signed certificate and show you how to validate the JWT token using Nimbus Jose JWT library.

package com.varra.samples;

import java.io.IOException;

import java.math.BigInteger;

import java.security.GeneralSecurityException;

import java.security.KeyFactory;

import java.security.KeyPair;

import java.security.KeyPairGenerator;

import java.security.PrivateKey;

import java.security.SecureRandom;

import java.security.cert.X509Certificate;

import java.security.interfaces.RSAPrivateKey;

import java.security.interfaces.RSAPublicKey;

import java.security.spec.X509EncodedKeySpec;

import java.util.Base64;

import java.util.Date;

import com.nimbusds.jose.JWSAlgorithm;

import com.nimbusds.jose.JWSHeader;

import com.nimbusds.jose.JWSSigner;

import com.nimbusds.jose.crypto.RSASSASigner;

import com.nimbusds.jose.crypto.RSASSAVerifier;

import com.nimbusds.jwt.JWTClaimsSet;

import com.nimbusds.jwt.SignedJWT;

import sun.security.rsa.RSAPublicKeyImpl;

import sun.security.x509.AlgorithmId;

import sun.security.x509.CertificateAlgorithmId;

import sun.security.x509.CertificateSerialNumber;

import sun.security.x509.CertificateValidity;

import sun.security.x509.CertificateVersion;

import sun.security.x509.CertificateX509Key;

import sun.security.x509.X500Name;

import sun.security.x509.X509CertImpl;

import sun.security.x509.X509CertInfo;

public class JWTTokenUtils {

/**

* Create a self-signed X.509 Certificate

* @param dn the X.509 Distinguished Name, eg "CN=RK, L=Hyderabad, C=Hyderabad"

* @param pair the KeyPair

* @param days how many days from now the Certificate is valid for

* @param algorithm the signing algorithm, eg "SHA1withRSA"

public static X509Certificate generateCertificate(String dn, KeyPair pair, int days, String algorithm)

throws GeneralSecurityException, IOException

{

PrivateKey privkey = pair.getPrivate();

X509CertInfo info = new X509CertInfo();

Date from = new Date();

Date to = new Date(from.getTime() + days * 86400000l);

CertificateValidity interval = new CertificateValidity(from, to);

BigInteger sn = new BigInteger(64, new SecureRandom());

X500Name owner = new X500Name(dn);

info.set(X509CertInfo.VALIDITY, interval);

info.set(X509CertInfo.SERIAL_NUMBER, new CertificateSerialNumber(sn));

//info.set(X509CertInfo.SUBJECT, new CertificateSubjectName(owner));

info.set(X509CertInfo.SUBJECT, owner);

info.set(X509CertInfo.ISSUER, owner);

info.set(X509CertInfo.KEY, new CertificateX509Key(pair.getPublic()));

info.set(X509CertInfo.VERSION, new CertificateVersion(CertificateVersion.V3));

AlgorithmId algo = new AlgorithmId(AlgorithmId.md5WithRSAEncryption_oid);

info.set(X509CertInfo.ALGORITHM_ID, new CertificateAlgorithmId(algo));

// Sign the cert to identify the algorithm that's used.

X509CertImpl cert = new X509CertImpl(info);

cert.sign(privkey, algorithm);

// Update the algorith, and resign.

algo = (AlgorithmId)cert.get(X509CertImpl.SIG_ALG);

info.set(CertificateAlgorithmId.NAME + "." + CertificateAlgorithmId.ALGORITHM, algo);

cert = new X509CertImpl(info);

cert.sign(privkey, algorithm);

return cert;

}

public static String generateToken(RSAPrivateKey privateKey) throws Exception

{

// Create RSA-signer with the private key

final JWSSigner signer = new RSASSASigner(privateKey);

// Prepare JWT with claims set

final JWTClaimsSet claimsSet = new JWTClaimsSet.Builder()

.subject("alice")

.issuer("Rajakrishna Reddy")

.claim("user", "Rajakrishna Reddy")

.claim("email", "abc@xyz.com")

.claim("tenantId", "123")

.expirationTime(new Date(new Date().getTime() + 60 * 1000))

.build();

final SignedJWT signedJWT = new SignedJWT(new JWSHeader(JWSAlgorithm.RS256), claimsSet);

signedJWT.sign(signer);

return signedJWT.serialize();

}

public static boolean isValidToken(String token, RSAPublicKey publicKey) throws Exception

{

return SignedJWT.parse(token).verify(new RSASSAVerifier(publicKey));

}

public static boolean isValidToken(String token, String publicKey) throws Exception

{

byte[] decoded = Base64.getDecoder().decode(publicKey);

X509EncodedKeySpec spec = new X509EncodedKeySpec(decoded);

KeyFactory kf = KeyFactory.getInstance("RSA");

RSAPublicKey generatePublic = (RSAPublicKey) kf.generatePublic(spec);

BigInteger modulus = generatePublic.getModulus();

BigInteger exponent = generatePublic.getPublicExponent();

return SignedJWT.parse(token).verify(new RSASSAVerifier(new RSAPublicKeyImpl(modulus, exponent)));

//return SignedJWT.parse(token).verify(new RSASSAVerifier(publicKey));

}

public static void main(String[] args) throws Exception {

final String algorithmType = "RSA";

final String algorithm = "SHA256withRSA";

final String dn = "CN=Rajakrishna Reddy, OU=OU, O=varra, L=Hyderabad, ST=TL, C=IN";

final int days = 365;

final KeyPairGenerator keyGenerator = KeyPairGenerator.getInstance(algorithmType);

keyGenerator.initialize(2048);

final KeyPair kp = keyGenerator.genKeyPair();

final X509Certificate certificate = generateCertificate(dn, kp, days, algorithm);

System.out.println("X09.Certificate: "+certificate);

//final String token = generateToken((RSAPrivateKey) kp.getPrivate());

final String token = "eyJhbGciOiJSUzI1NiJ9.eyJleHAiOjE1MjUyNDUyMDAsInN1YiI6IkpXVCIsInVzZXJfbWV0YWRhdGEiOiJ7XCJVc2VybmFtZVwiOlwibWNzYVwifSIsImlhdCI6MTUyNTE1ODgwMH0.wbroKZfrdGPGnk3OaPWbRr56rRzkg4DFO999jmSsut8IYAthKU0f26CIjWfrNPXD5asV74JYIS49VFNkFwbWfnIFETY1CaLIIm6F6NP5cFE7LW5G-y0qNRaCJgOLaFV4z4lsQOi0KAfuFVckiL5EHxhyBks-MCQEXMWO2JIBBZjAxhIH7fmhMHsYQQUxvm8Tx1dpnbvyh9E6x5F9BNZeS2DcBCqvzCuSUAz2DbgsJ-gVyrDRJgcItiCnscZy2u3sZq3XBTK2qBiSIpS4zVZupVS0f-5v57y7BvdVX2siuu-StN5614zvON_MJRgNLdo1yA1Y5F8eJ9IZrelMWB5GZw";

final String publiKey = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA2hg1nqteEY12r5AO/enYD14aXEUaoqgvhtcHDwEPQwf9KqGpwoeC8jQE1qHfb2K1Wm/o4ug60Kv02f7AEJiNrUuKe9MYJdTr/DhekVrE0ttJkGCjLoNiVgMZHKH557Ouf6RsWJc5QjUiqxg6azwYUuHu2U199MZzFXvAVVUQR+hh8YqQM4KIQytOpj1JhxH7hQehth9vF5kIhA+K8htIIO04UF9+8ScrBHMQgj9q0RLperVQLxGsYT8cEZIn9tv1r47jynrTS0z/Vq2uVMGRg/bRPuo598++XUIglM92Ehbih87j//ATcHtsabefzBAVQuN4OaqLTT375JRAWpoWmQIDAQAB";

System.out.println("Token: "+token);

//System.out.println("Is valid?: "+isValidToken(token, (RSAPublicKey) kp.getPublic()));

System.out.println("Is valid?: "+isValidToken(token, publiKey));

//System.out.println(isValidToken(token, CertificateUtil.parseRSAPublicKey()));

}

How to remove untracked/ignored files and directories from git local repository

noreply@blogger.com (Rajakrishna Reddy) — Tue, 19 Dec 2017 07:30:00 +0000

There is always be a need to remove the unwanted files and directories from the git to clean the git local repo, but sometimes it's a tedious job to do if we are not aware of some simple cool features that are offered by git, such as git clean, there is a wonderful and informative article available in git docs.

Here I wanted to give you some useful commands that do the required job of cleaning the untracked or ignored files and directories from the git repo.

This is written according to the git documentation provided here. This should not be considered as a complete guide to git clean.

Run this command to see what are the files or dirs going be removed: git clean -n or git clean --dry-run

So it doesn't actually remove anything, just show what would be done.
Run this command to delete the files or directories actually: git cleanBeware that it removes the files and directories permanently!!

If you want to remove directories, run git clean -f -d or git clean -fd
If you want to remove ignored files, run git clean -f -X or git clean -fX
If you want to remove ignored and non-ignored files, run git clean -f -x or git clean -fx

It is always advisable to have a glance at the complete documentation at git! Have a look at git clean documentation for a clear understanding.

How to add line numbers attributes to java class files

noreply@blogger.com (Rajakrishna Reddy) — Mon, 04 Dec 2017 11:32:00 +0000

Add this info to your javac command to add line number attributes to the generated class files:

javac debug="true" debuglevel="lines,vars,source" includeantruntime="true"

[Solved] ORA-01034: ORACLE not available

noreply@blogger.com (Rajakrishna Reddy) — Tue, 07 Nov 2017 09:22:00 +0000

Have you got stuck up with this error in Oracle DB startup?? Here is the solution:

D:\oracle\code>sqlplus system/Admin123@xe

SQL*Plus: Release 11.2.0.2.0 Production on Tue Nov 7 14:44:36 2017

ERROR:

ORA-01034: ORACLE not available

ORA-27101: shared memory realm does not exist

Process ID: 0

Session ID: 0 Serial number: 0

Enter user-name: system

Enter password:

ERROR:

ORA-01034: ORACLE not available

ORA-27101: shared memory realm does not exist

Process ID: 0

Session ID: 0 Serial number: 0

Enter user-name:

D:\oracle\code>sqlplus / as sysdba

SQL*Plus: Release 11.2.0.2.0 Production on Tue Nov 7 14:45:00 2017

Connected to an idle instance.

SQL>

SQL> startup

ORACLE instance started.

Total System Global Area 1068937216 bytes

Fixed Size 2260048 bytes

Variable Size 637535152 bytes

Database Buffers 423624704 bytes

Redo Buffers 5517312 bytes

Database mounted.

SQL> exit

Disconnected from Oracle Database 11g Express Edition Release 11.2.0.2.0 - 64bit Production

D:\oracle\code>sqlplus system/Admin123@xe

SQL*Plus: Release 11.2.0.2.0 Production on Tue Nov 7 14:47:02 2017

Connected to:

Oracle Database 11g Express Edition Release 11.2.0.2.0 - 64bit Production

SQL> exit

Disconnected from Oracle Database 11g Express Edition Release 11.2.0.2.0 - 64bit Production

D:\oracle\code>

How can we add colors and format the text in console in python 3

noreply@blogger.com (Rajakrishna Reddy) — Thu, 03 Aug 2017 12:33:00 +0000

class color:     PURPLE = '\033[95m'     CYAN = '\033[96m'     DARKCYAN = '\033[36m'     BLUE = '\033[94m'     GREEN = '\033[92m'     YELLOW = '\033[93m'     RED = '\033[91m'     BOLD = '\033[1m'     UNDERLINE = '\033[4m'     END = '\033[0m'    print color.BOLD + 'Hello World !' + color.END

How to push NuGet package to NuGet server with ApiKey

noreply@blogger.com (Rajakrishna Reddy) — Tue, 14 Feb 2017 22:34:00 +0000

These are the simple 3 steps that you can run to achieve this:

v:\krishna\nuget.exe sources Add -Name TPaaS-Snapshot-nuget -Source https://artifactory.trimble.tools/artifactory/TPaaS-Snapshot-nuget/ -username {{username}} -password {{ApiKey}}
v:\krishna\nuget.exe setapikey {{username}}:{{ApiKey}} -source https://artifactory.trimble.tools/artifactory/TPaaS-Snapshot-nuget/
v:\krishna\nuget.exe push {{package-path}}.nupkg -Source TPaaS-Snapshot-nuget

Installing a custom color theme in WEBSTORM.

noreply@blogger.com (Rajakrishna Reddy) — Sat, 26 Nov 2016 15:01:00 +0000

Installing a custom color theme in WEBSTORM:

1) First goto /Users/rk/Library/Preferences/WebStorm2016.3

2) Add the color theme xml file under the colors dir.

3) Update the color theme name in options/color.sheme.xml file