Skip to main content

Linux Useful Commands with examples

To know the IP address
-----------
hostname -i (ip addres)
hostname -s (short name)
hostname -d (domain name)
hostname -v (host name with domain name)


To know the port number and running processes
netstat -ano | findstr 80

If the file is huge in size and to see the file content we can use
less <file name>
e.g. less service.log

Searching  matching pattern in file
grep '<matching text>' <file name>
e.g. grep 'Exception' service.log

To grep the text from .gz files
gzgrep '<matching text>' <gz file name>
e.g. gzgrep 'Exception' service.log.gz

ps -eaf | grep java
ps aus | grep java

tail -f <file Name> (auto updated last few lines)
tail -100 logfile.log  (last 100 lines)

ls -a  (hidden files)
ls -lrt (Sort the files by time stamp)

kill -9 <Process ID>   (get Process ID using ps -eaf | grep <process name>)
e.g. kill -9 30102

Comments

Post a Comment

Popular posts from this blog

"immutability" Nature of an Object

Immutability. A Java object is considered to be immutable when its state (properties and contents) cannot change after it is created. Use of immutable objects is widely accepted as a sound strategy for creating simple, reliable code. Immutable objects are particularly useful in concurrent applications. Since they cannot change state, they cannot be corrupted by thread interference or observed in an inconsistent state. java.lang.String and java.lang.Integer classes are the Examples of immutable Immutable objects are simple to use test and construct. Immutable objects are thread-safe by default. Immutable objects are good Map keys and Set elements (Since state of these objects must not change while stored in a collection). This is the reason most of the times we prefer String objects as Key in many Map Collection objects. Immutable objects do not require an implementation of clone. Immutable objects allow hashCode to use lazy initialization, and to cache its return value. To crea...
Post a Comment
Read more

Self Signed Certificates Vs Signed Certificates (CA Certificates)

Certificates Certificates basically two categories. Self Signed Certificates  - will create by self CA Certificates  - will be  provided by Third party vendor with robust algorithms Depends on the location of installing the certificate these are two types 1. Public Key Certificates (Client Side) 2. Private Key Certificates (Server Side) Self Signed Certificates   If any one is using self signed certificates in their applications they have to make sure both server side and client side certificates are in sync. Other wise we should be ready to face SSLHandShake Exceptions. These will be preferable mostly for lower environments not for production. CA certificates  If you install CA certificates on server side, client side certificates are installed automatically whenever they access the server. So in production for CA certificates there is no need to install the client side certificates. We can generate a Self Signed Certificate using Java Key tool JAVA_HOME/bi...
1 comment
Read more

Finding Second Highest element in an Array

package com.sbs.java8.praticse; public class SecondHightestClass { public static void main(String[] args) { final Integer[] intArray = { 10, 2, 36, 7, 29, 30, 100, 20, 90, 83, 87 }; final int n = intArray.length; int sortPointer = intArray.length; for (int m = n; m > (n - sortPointer); m--) { for (int i = 0; i < n - 1; i++) { int j = i + 1; if (intArray[i] > intArray[j]) { int temp = intArray[i]; intArray[i] = intArray[j]; intArray[j] = temp; } } sortPointer--; } System.out.println(intArray[n - 2]); } }
Post a Comment
Read more