Learn Linux administration

Tuesday, August 23, 2016

find files with and without matching string in Linux

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Find all files without string "successfully completed" in directory
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find /home/oracle/test -type f | xargs grep -L "successfully completed"

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Find all files with macthing string "successfully completed" in directory
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find /home/oracle/test -type f | xargs grep -l -n "successfully completed"

Monday, March 14, 2016

change hostname on a linux machine -centos

I want to change my Linux hostname from Linux01 to Linux03

[root@Linux01 Desktop]# vi /etc/sysconfig/network

[root@Linux01 Desktop]# cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=Linux03

************************************************************************
YOU MIGHT ALSO WANT TO CHECK THE /ETC/HOSTS FILE FOR IP SETTINGS
************************************************************************

RESTART THE SERVER NOW. AFTER REBOOT

[oracle@Linux03 Desktop]$ hostname
Linux03

[oracle@Linux03 Desktop]$

Configure gmail to send emails from your Linux machine

In this how to, I assume you already have a running CentOS 6.7 server. I am going to share how to install and setup ssmtp.x86_64 0:2.61-22.el5 on CentOS 6.7 version. This how to has been tested with mutt-1.5.20-7 as a mail client.

First, we must ensure everything are up to date by running the following commands: –

[root@Linux01 Desktop]# wget -c http://dl.fedoraproject.org/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm

Resolving dl.fedoraproject.org... 209.132.181.26, 209.132.181.25, 209.132.181.23, ...
Connecting to dl.fedoraproject.org|209.132.181.26|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 12232 (12K) [application/x-rpm]
Saving to: “epel-release-5-4.noarch.rpm”

100%[==================================================================================================================>] 12,232 --.-K/s in 0s

2016-02-22 09:50:52 (93.2 MB/s) - “epel-release-5-4.noarch.rpm” saved [12232/12232]

[root@Linux01 Desktop]# rpm -ivh epel-release-5-4.noarch.rpm
Preparing... ########################################### [100%]
1:epel-release ########################################### [100%]
[root@Linux01 Desktop]# yum -y install ssmtp
Loaded plugins: fastestmirror, refresh-packagekit, security
Setting up Install Process
Loading mirror speeds from cached hostfile
* base: mirror-centos.hostingswift.com
* epel: archive.linux.duke.edu
* extras: mirror.sesp.northwestern.edu
* updates: mirror-centos.hostingswift.com
base | 3.7 kB 00:00
epel | 3.6 kB 00:00
epel/primary_db | 2.9 MB 00:01
extras | 3.4 kB 00:00
updates | 3.4 kB 00:00
updates/primary_db | 3.9 MB 00:03
Resolving Dependencies
--> Running transaction check
---> Package ssmtp.x86_64 0:2.61-22.el5 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

============================================================================================================================================================
Package Arch Version Repository Size
============================================================================================================================================================
Installing:
ssmtp x86_64 2.61-22.el5 epel 55 k

Transaction Summary
============================================================================================================================================================
Install 1 Package(s)

Total download size: 55 k
Installed size: 93 k
Downloading Packages:
:
:
:
: 1/1

Installed:
ssmtp.x86_64 0:2.61-22.el5

Complete!

[root@Linux01 Desktop]# help sendmail
bash: help: no help topics match `sendmail'. Try `help help' or `man -k sendmail' or `info sendmail'.
[root@Linux01 Desktop]# man -k sendmail
sendmail (1) - Postfix to Sendmail compatibility interface
sendmail (8) - Postfix to Sendmail compatibility interface

[root@Linux01 Desktop]# cd /etc/ssmtp
[root@Linux01 ssmtp]# ls -ll
total 8
-rw-r--r--. 1 root root 200 Apr 16 2001 revaliases
-rw-r-----. 1 root mail 1371 Jan 12 2015 ssmtp.conf
[root@Linux01 ssmtp]# mv /etc/ssmtp/ssmtp.conf /etc/ssmtp/ssmtp.conf.ori
[root@Linux01 ssmtp]# touch /etc/ssmtp/ssmtp.conf
[root@Linux01 ssmtp]# mv /etc/ssmtp/revaliases /etc/ssmtp/revaliases.orig
[root@Linux01 ssmtp]# touch /etc/ssmtp/revaliases
[root@Linux01 ssmtp]# vi /etc/ssmtp/ssmtp.conf
[root@Linux01 ssmtp]# vi /etc/ssmtp/revaliases

Next, we will configure sSMTP to forward email to any shared hosting server either running CPanel or DirectAdmin.

Include the following below in /etc/ssmtp/ssmtp.conf file: –

root=postmaster
mailhub=mail.yourdomain.com:587
Hostname=localhost
FromLineOverride=YES
AuthUser=abcd@yourdomain.com
AuthPass=YourPassWord
UseSTARTTLS=YES

Include the following below in /etc/ssmtp/revaliases file: –

root:username@yourdomain.com:mail.yourdomain.com:587

Include the following below in /root/.muttrc file: –

set envelope_from=yes
set from="username@yourdomain.com"
set realname="Prefer From Display"

You can use GMAIL server to forward your mails. Use below seetings to configure the GMAIL SMTP

If you an option to forward email to Gmail server, you can configure using steps below.

Replace previous configuration to below in /etc/ssmtp/ssmtp.conf file: –

root=postmaster
mailhub=smtp.gmail.com:587
Hostname=abcd@gmail.com
FromLineOverride=YES
AuthUser=abcd@gmail.com
AuthPass=YourPassWord
UseSTARTTLS=YES

Replace previous configuration to below in /etc/ssmtp/revaliases file: –

root:username@gmail.com:smtp.gmail.com:587

Replace previous configuration to below in /root/.muttrc file: –

set envelope_from=yes
set from="abcd@gmail.com"
set realname="Prefer From Display"

Next, you can start sending email using your preferred email server using command below: –

[root@Linux01 ~]# echo "Testing outgoing email" | mutt -s "Testing" arvind.toorpu@nelnet.net
bash: mutt: command not found
[root@Linux01 ~]# yum install mutt
Loaded plugins: fastestmirror, refresh-packagekit, security
Setting up Install Process
Loading mirror speeds from cached hostfile
* base: mirror-centos.hostingswift.com
* epel: mirror.steadfast.net
* extras: mirror.sesp.northwestern.edu
* updates: mirror-centos.hostingswift.com
Resolving Dependencies
--> Running transaction check
---> Package mutt.x86_64 5:1.5.20-7.20091214hg736b6a.el6 will be installed
--> Processing Dependency: urlview for package: 5:mutt-1.5.20-7.20091214hg736b6a.el6.x86_64
--> Processing Dependency: libtokyocabinet.so.8()(64bit) for package: 5:mutt-1.5.20-7.20091214hg736b6a.el6.x86_64
--> Running transaction check
---> Package tokyocabinet.x86_64 0:1.4.33-6.el6 will be installed
---> Package urlview.x86_64 0:0.9-7.el6 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

============================================================================================================================================================
Package Arch Version Repository Size
============================================================================================================================================================
Installing:
mutt x86_64 5:1.5.20-7.20091214hg736b6a.el6 base 1.2 M
Installing for dependencies:
tokyocabinet x86_64 1.4.33-6.el6 base 428 k
urlview x86_64 0.9-7.el6 base 24 k

Transaction Summary
============================================================================================================================================================
Install 3 Package(s)

Total download size: 1.7 M
Installed size: 5.6 M
Is this ok [y/N]: y
Downloading Packages:
(1/3): mutt-1.5.20-7.20091214hg736b6a.el6.x86_64.rpm | 1.2 MB 00:00
(2/3): tokyocabinet-1.4.33-6.el6.x86_64.rpm | 428 kB 00:00
(3/3): urlview-0.9-7.el6.x86_64.rpm | 24 kB 00:00
------------------------------------------------------------------------------------------------------------------------------------------------------------
Total 1.5 MB/s | 1.7 MB 00:01
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : tokyocabinet-1.4.33-6.el6.x86_64 1/3
Installing : urlview-0.9-7.el6.x86_64 2/3
Installing : 5:mutt-1.5.20-7.20091214hg736b6a.el6.x86_64 3/3
Verifying : 5:mutt-1.5.20-7.20091214hg736b6a.el6.x86_64 1/3
Verifying : urlview-0.9-7.el6.x86_64 2/3
Verifying : tokyocabinet-1.4.33-6.el6.x86_64 3/3

Installed:
mutt.x86_64 5:1.5.20-7.20091214hg736b6a.el6

Dependency Installed:
tokyocabinet.x86_64 0:1.4.33-6.el6 urlview.x86_64 0:0.9-7.el6

Complete!
[root@Linux01 ~]# vi /root/.muttrc
[root@Linux01 ~]# clear

[root@Linux01 ~]# echo "Testing outgoing email" | mutt -s "Testing" abcd@gmail.com
[root@Linux01 ~]# clear

Finally, with all the configuration above I hope you are able to use and enjoy your sSMTP to send an email. Thank you.

script to check if the file exists

#!/usr/bin/ksh
## This is a simple script to check if the file exists in a dir or not
## Created by : Arvind Reddy
## This will prompt for

echo " file name please : "
read FILENAME;
export dataDir=/u01/app/oracle/dpump;
sourceFile=SCOTT.dmp;

cd /u01/app/oracle/dpump;
echo `pwd`

##Did we get a file?

if [ -e ${dataDir}/${sourceFile} ];then
echo "Found file !! "
else
echo " No file found !!! "
fi

Linux os level backup and cleanup cmds

REMOVE ALL FILES OLDER THAN 15 DAYS:

[oracle@Linux01 dpump]$
find /u01/app/oracle/dpump/*.dmp -mtime +15 -exec rm {} \;

GZIP ALL FILES OLDER THAN 15 DAYS: (This will make individual GZIP files)

[oracle@Linux01 dpump]$
find /u01/app/oracle/dpump/*.dmp -mtime +90 -exec gzip {} \;

MOVE FILES OLDER THAN 15DAYS

find /home/arvind -maxdepth 1 -iname "*.txt" -mtime -15 -exec mv {} /home/arvind/test1/ \;

COUNT FILES OLDER THAN 90 DAYS

find /u01/app/oracle/admin/adump/*.aud -mtime +90 | exec wc -l {} \;

TAR ALL FILES OLDER THAN 15 DAYS:
(This will make 1 TAR FILE With date format at end)

[oracle@Linux01 dpump]$

find /u01/app/oracle/admin/ORCL/adump/*.aud -mtime +90 | xargs tar -czvPf /u01/app/oracle/admin/ORCL/adump/ARCH_AUD_$(date +%F).tar.gz

Wednesday, February 24, 2016

Convert all text in a file from UPPER to lowercase on LINUX

Convert all text in a file from UPPER to lowercase

To translate or delete characters use tr command. The basic syntax is:

Lets create a simple text file with mix of lower and upper case chars :
oracle@Linux01:[/u01/app/oracle/admin/bin] $ vi TGTGTG.txt

oracle@Linux01:[/u01/app/oracle/admin/bin] $ cat TGTGTG.txt
as This IS in Upper

Here I am passing the TGTGTG.txt as inprt and converting the output to lower case:
oracle@Linux01:[/u01/app/oracle/admin/bin] $ tr '[:upper:]' '[:lower:]' < TGTGTG.txt > output.txt

oracle@Linux01:[/u01/app/oracle/admin/bin] $ cat output.txt
as this is in upper

Here I am passing the TGTGTG.txt as inprt and converting the output to UPPER case:
oracle@Linux01:[/u01/app/oracle/admin/bin] $ tr '[:lower:]' '[:upper:]' < TGTGTG.txt > output_UP.txt

oracle@Linux01:[/u01/app/oracle/admin/bin] $ cat output_UP.txt
AS THIS IS IN UPPER

oracle@Linux01:[/u01/app/oracle/admin/bin] $

EXIT status messages in NIX

Exit Status

By default in Linux if particular command/shell script is executed, it return two type of values which is used to see whether command or shell script executed is successful or not.

(1) If return value is zero (0), command is successful.
(2) If return value is nonzero, command is not successful or some sort of error executing command/shell script.

This value is know as Exit Status.

But how to find out exit status of command or shell script?
Simple, to determine this exit Status you can use $? special variable of shell.

For e.g. If I want to remove a non-existing file

$ rm ABCD
rm: cannot remove `ABCD': No such file or directory
and after that if you give command
$ echo $?
it will print nonzero value to indicate error. Now give command

$ ls
$ echo $?
It will print 0 to indicate command is successful.

Exercise
Try these exit status and check for yourself:

$ expr 1 + 3
$ echo $?

$ echo Welcome
$ echo $?

$ wildwest canwork?
$ echo $?

$ date
$ echo $?

$ echon $?
$ echo $?