How to Find a List of All Open Files in Linux/UNIX

How to find list of all open files in Linux/UNIX

Its really very simple to find the list of open files on UNIX/Linux. As you know Linux/UNIX kernel has many powerful commands which helps a lot.

For checking the list of all open files on your system, you can use the command

Command :-

lsof

lsof - list open files , this has many command options.Some important options as below :

-p - for specific PID
-u - for specific user


Example :-

lsof -u manoj


Output :-

lsof      9963 manoj  mem       REG                8,1     52120 11276171 /lib/x86_64-linux-gnu/libnss_files-2.15.so
lsof      9963 manoj  mem       REG                8,1     47680 11276175 /lib/x86_64-linux-gnu/libnss_nis-2.15.so
lsof      9963 manoj  mem       REG                8,1     97248 11276165 /lib/x86_64-linux-gnu/libnsl-2.15.so
lsof      9963 manoj  mem       REG                8,1     35680 11276167 /lib/x86_64-linux-gnu/libnss_compat-2.15.so
lsof      9963 manoj  mem       REG                8,1   7224832  5511486 /usr/lib/locale/locale-archive
lsof      9963 manoj  mem       REG                8,1   1815224 11276120 /lib/x86_64-linux-gnu/libc-2.15.so
lsof      9963 manoj  mem       REG                8,1    149280 11276100 /lib/x86_64-linux-gnu/ld-2.15.so
lsof      9963 manoj  mem       REG                8,1     26258  5769171 /usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache
lsof      9963 manoj    0u      CHR              136,0       0t0        3 /dev/pts/0
lsof      9963 manoj    1u      CHR              136,0       0t0        3 /dev/pts/0
lsof      9963 manoj    2u      CHR              136,0       0t0        3 /dev/pts/0
lsof      9963 manoj    3r      DIR                0,3         0        1 /proc
lsof      9963 manoj    4r      DIR                0,3         0    64363 /proc/9963/fd
lsof      9963 manoj    5w     FIFO                0,8       0t0    64368 pipe
lsof      9963 manoj    6r     FIFO                0,8       0t0    64369 pipe
lsof      9964 manoj  cwd       DIR                8,1      4096  3932162 /home/manoj
lsof      9964 manoj  rtd       DIR                8,1      4096        2 /
lsof      9964 manoj  txt       REG                8,1    131312  5505664 /usr/bin/lsof
lsof      9964 manoj  mem       REG                8,1     52120 11276171 /lib/x86_64-linux-gnu/libnss_files-2.15.so
lsof      9964 manoj  mem       REG                8,1     47680 11276175 /lib/x86_64-linux-gnu/libnss_nis-2.15.so
lsof      9964 manoj  mem       REG                8,1     97248 11276165 /lib/x86_64-linux-gnu/libnsl-2.15.so
lsof      9964 manoj  mem       REG                8,1     35680 11276167 /lib/x86_64-linux-gnu/libnss_compat-2.15.so
lsof      9964 manoj  mem       REG                8,1   7224832  5511486 /usr/lib/locale/locale-archive
lsof      9964 manoj  mem       REG                8,1   1815224 11276120 /lib/x86_64-linux-gnu/libc-2.15.so
lsof      9964 manoj  mem       REG                8,1    149280 11276100 /lib/x86_64-linux-gnu/ld-2.15.so

Apart from there are many other options you can use to find more powerful lsof command.

Example 2:-

manoj@manoj-HP-ProBook-6450b:~$ ps -ef | lsof -p 9987
COMMAND    PID USER   FD      TYPE DEVICE SIZE/OFF NODE NAME
kworker/u 9987 root  cwd   unknown                      /proc/9987/cwd (readlink: Permission denied)
kworker/u 9987 root  rtd   unknown                      /proc/9987/root (readlink: Permission denied)
kworker/u 9987 root  txt   unknown                      /proc/9987/exe (readlink: Permission denied)
kworker/u 9987 root NOFD                                /proc/9987/fd (opendir: Permission denied)

Linux / Unix: Find and Remove Files with One Command

This is really very easy in Linux/Unix. This is the reason why Linux/Unix is so popular in most of the industries.  

COMMAND :-

find - search for files in a directory hierarchy

 

SYNOPSIS 

find [-H] [-L] [-P] [-D debugopts] [-Olevel] [path...] [expression]

SYNTAX

find <dir-name> <criteria> <action>

dir-name - The directory which you want to search.
criteria - This is searching criteria, what you want to search.
action(if required) - This is command action you want to execute.

There are many options or expressions you can use to find your relevant files and folders.

Example :- The below command for finding all files with extension .xml

dev@jdg-developer-desktop ~ $ find soap_projects/  -name "*.xml"
 
soap_projects/folk-enabler-no-sec--soapui-project.xml
soap_projects/aim-localhost-tomcat-soapui-project.xml
soap_projects/roamenable-service-soapui-project.xml
soap_projects/search-enabler-soapui-project.xml

Find all the files , which file name contains "data" and extensions with .txt

dev@jdg-developer-desktop ~/workspace_test $ find .  -name "*data*.txt"  

./test_data_file.txt

Example for finding and delete all all files with "find" command.

find . -name "*data*.txt" -exec rm -rf {} \;

Example for finding and delete all .xml files.

find / -name "*.xml" -exec rm -f {} \;

Example for finding and delete all .xml files.

find /searchdirectory -name "*.xml" -exec rm -f {} \;

Delete command for all file with find command result :-

-exec rm -rf {} \;

How to Install SQL*Plus Client on Linux

Its really very simple steps to do this, and very crazy while dependency for compatibility with OS (x32 bit or x64 bit).

I have done for x64 bit Linux UBUNTU. Generally Oracle provides .rpm packages , and you need to download those packages into  your machine.

Download here.

Assuming that you have already installed Oracle Database , else you are connecting some remote database. Because, this post only show the sqlplus installation to connect existing database.

Downloaded files :-

oracle-instantclient12.1-basic-12.1.0.2.0-1.x86_64.rpm
oracle-instantclient12.1-devel-12.1.0.2.0-1.x86_64.rpm
oracle-instantclient12.1-sqlplus-12.1.0.1.0-1.x86_64.rpm
Copy these files to your preferred location. I have  used below location.

/usr/java

Now time for convert these .rpm packages into Debian specific package and install on your Ubuntu. Use alien command to convert.

Follow the below steps and install one-by-one.

First install the sqlplus :-

dev@javadevelopersguide-developer-desktop /usr/java $ sudo alien -i oracle-instantclient12.1-sqlplus-12.1.0.1.0-1.x86_64.rpm

[sudo] password for dev:

dpkg --no-force-overwrite -i oracle-instantclient12.1-sqlplus_12.1.0.1.0-2_amd64.deb

Selecting previously unselected package oracle-instantclient12.1-sqlplus.

(Reading database ... 226951 files and directories currently installed.)

Unpacking oracle-instantclient12.1-sqlplus (from oracle-instantclient12.1-sqlplus_12.1.0.1.0-2_amd64.deb) ...

Setting up oracle-instantclient12.1-sqlplus (12.1.0.1.0-2) ...

Second install the basic (packages) :-

dev@javadevelopersguide-developer-desktop /usr/java $ sudo alien -i oracle-instantclient12.1-basic-12.1.0.2.0-1.x86_64.rpm
dpkg --no-force-overwrite -i oracle-instantclient12.1-basic_12.1.0.2.0-2_amd64.deb

Selecting previously un-selected package oracle-instantclient12.1-basic.

(Reading database ... 226963 files and directories currently installed.)

Unpacking oracle-instantclient12.1-basic (from oracle-instantclient12.1-basic_12.1.0.2.0-2_amd64.deb) ...

Setting up oracle-instantclient12.1-basic (12.1.0.2.0-2) ...

Processing triggers for libc-bin ...

ldconfig deferred processing now taking place 

Third install the devel :-

dev@javadevelopersguide-developer-desktop /usr/java $ sudo alien -i oracle-instantclient12.1-devel-12.1.0.2.0-1.x86_64.rpm

dpkg --no-force-overwrite -i oracle-instantclient12.1-devel_12.1.0.2.0-2_amd64.deb

Selecting previously unselected package oracle-instantclient12.1-devel.

(Reading database ... 226981 files and directories currently installed.)

Unpacking oracle-instantclient12.1-devel (from oracle-instantclient12.1-devel_12.1.0.2.0-2_amd64.deb) ...

Setting up oracle-instantclient12.1-devel (12.1.0.2.0-2) ...

Once these installation complete, you can start sqlplus using below command. Either you can use your specific user/password with correct server address.

dev@javadevelopersguide-developer-desktop /usr/java $ sqlplus / as sysdba

Good to go if no error, else follow with fixing below !! Good luck.

Note - You may face the below library missing issue while executing sqlplus command. Error below :-

dev@javadevelopersguide-developer-desktop /usr/java $ sqlplus / as sysdba

sqlplus: error while loading shared libraries: libsqlplus.so: cannot open shared object file: No such file or directory


Now this issue saying the lib is not loading, the sqlplus is complaining about the missing library.

So you need to edit the oracle.conf and provide the correct lib path (i.e : /usr/lib/oracle/12.1/client64/lib).Add this path into oracle.conf file.

dev@javadevelopersguide-developer-desktop /usr/java $ sudo vi /etc/ld.so.conf.d/oracle.conf

/usr/lib/oracle/12.1/client64/lib

Now, you should be able to connect to your preferred Database. I have connected to our remote server as below :

dev@javadevelopersguide-developer-desktop /usr/java $ sqlplus my_user/my_password@z2customdb01.ztest/z2custom.zenv.mycompanyadd.com.in
SQL*Plus: Release 12.1.0.1.0 Production on Wed Dec 23 16:30:02 2015
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Last Successful login time: Wed Dec 23 2015 16:18:22 +11:00

Connected to:

Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production

With the Partitioning option
SQL>

SQL>

How to Find the Amount of RAM in a Linux Machine

How to find the number of RAM in Linux Machine (i.e. Mint OS). Its working for Mint OS and tested. 

sudo lshw -short

Example -

 

dev@developer-desktop $ sudo lshw -short
[sudo] password for dev:

H/W path Device Class Description

=========================================================
system 4518B8M (To be filled by O.E.M.)
/0 bus Motherboard
/0/0 memory 64KiB BIOS
/0/4 processor Intel(R) Core(TM) i5-2400 CPU @ 3.10GHz
/0/4/5 memory 128KiB L1 cache
/0/4/6 memory 1MiB L2 cache
/0/4/7 memory 6MiB L3 cache
/0/1b memory 4GiB System Memory
/0/1b/0 memory DIMMProject-Id-Version: lshwReport-Msgid-Bugs-To: FULL NAME <EMAIL@ADDRESS>POT-Creation-Date: 2009-10-08 14:02+0200PO-Revision-Date: 2012-02-02 13:04+0000Last-T
/0/1b/1 memory 2GiB DIMM DDR3 Synchronous 1333 MHz (0.8 ns)
/0/1b/2 memory DIMMProject-Id-Version: lshwReport-Msgid-Bugs-To: FULL NAME <EMAIL@ADDRESS>POT-Creation-Date: 2009-10-08 14:02+0200PO-Revision-Date: 2012-02-02 13:04+0000Last-T
/0/1b/3 memory 2GiB DIMM DDR3 Synchronous 1333 MHz (0.8 ns)
/0/100 bridge 2nd Generation Core Processor Family DRAM Controller
/0/100/2 display 2nd Generation Core Processor Family Integrated Graphics Controller
/0/100/16 communication 6 Series/C200 Series Chipset Family MEI Controller #1
/0/100/16.3 communication 6 Series/C200 Series Chipset Family KT Controller
/0/100/19 eth0 network 82579LM Gigabit Network Connection
/0/100/1a bus 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2
/0/100/1b multimedia 6 Series/C200 Series Chipset Family High Definition Audio Controller
/0/100/1d bus 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1
/0/100/1e bridge 82801 PCI Bridge
/0/100/1f bridge Q67 Express Chipset Family LPC Controller
/0/100/1f.2 scsi0 storage 6 Series/C200 Series Chipset Family SATA AHCI Controller
/0/100/1f.2/0 /dev/sda disk 250GB WDC WD2500AAKX-0
/0/100/1f.2/0/1 /dev/sda1 volume 96GiB EXT4 volume
/0/100/1f.2/0/2 /dev/sda2 volume 52GiB Extended partition
/0/100/1f.2/0/2/5 /dev/sda5 volume 51GiB Linux filesystem partition
/0/100/1f.2/0/2/6 /dev/sda6 volume 1469MiB Linux filesystem partition
/0/100/1f.2/1 /dev/cdrom disk DVD RW AD-7250H
/0/100/1f.3 bus 6 Series/C200 Series Chipset Family SMBus Controller
/1 power To Be Filled By O.E.M.
/2 power To Be Filled By O.E.M.

Above I have highlighted with red color , it shows 2 slots is reserved for 2 RAM. Hope it will help you.

How to Set Java Version in Linux

How to set java version in Linux or Unix.

Here I have used Linux Mint, but this setup can work for other Linux distributions. 

Checking the existing java version on your linux machine.
dev@developer-desktop ~ $ java -version
java version "1.6.0_36"
OpenJDK Runtime Environment (IcedTea6 1.13.8) (6b36-1.13.8-0ubuntu1~12.04)
OpenJDK 64-Bit Server VM (build 23.25-b01, mixed mode)

 
The above command shows the existing java version installed on this machine. Now I can check the alternative version to set. These alternative versions are available for installation. The below command will prompt with sudo password and selection number. Try with below command :


dev@developer-desktop ~ $ sudo update-alternatives --config java
[sudo] password for dev: ***********
There are 3 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
------------------------------------------------------------
* 0            /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java   1061      auto mode
  1            /usr/bin/gij-4.6                                 1046      manual mode
  2            /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java   1061      manual mode
  3            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1051      manual mode

Press enter to keep the current choice[*], or type selection number: 3
update-alternatives: using /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java to provide /usr/bin/java (java) in manual mode.

In the above command, I have opted the Selection 3 , because I want java 1.7 version. You can choose as per your requirements. 

Now you can check whether version 7 is installed or not ? Try the check version command again as below.

dev@developer-desktop ~ $ java -version
java version "1.7.0_79" -----> This is newly installed.
OpenJDK Runtime Environment (IcedTea 2.5.6) (7u79-2.5.6-0ubuntu1.12.04.1)
OpenJDK 64-Bit Server VM (build 24.79-b02, mixed mode)



Hope this will help you.

Ubuntu Terminal Is Not Working Properly in Vi Editor

Ubuntu terminal is not working properly in vi Editor

As we all know vi editor is one of the major editing tool for developers. Sometimes its obvious to handle the issue if its not response properly. There are few scenario where this kind of behavior occurs. 

If you have newly installed the Ubuntu , or you have not updated the terminal with latest update. 

Just try to update the terminal by using below command.

sudo apt-get update

Now check your vi editor behavior , if not yet resolved then try the below command to install the vi (vim) editor.

Install Vim Editor using below command :-

sudo apt-get install vim

Now check your vi editor, I hope its fixed. It worked for me and its working awesome :)

How to Convert Epoch Time to Human-Readable Format in Unix

How to convert epoch to human readable format in UNIX ?

In this example the epoch time is 1432783870. Use the below command to convert the epoch time to human readable time.Technically epoch time known as UNIX time , also known as POSIX time. 

Example :-

dev@javadevelopersguide-developer-desktop ~/Epoch/ $ date -d @1432783870
Thu May 28 13:31:10 EST 2015
dev@javadevelopersguide-developer-desktop ~/Epoch/ $ date -d @1377360000
Sun Aug 25 02:00:00 EST 2013

Find more here.