learn linux, linux expert

Sunday, 12 June 2016

Install VLC PLAYER IN CENTOS

rpm -Uvh http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
rpm -Uvh http://li.nux.ro/download/nux/dextop/el6/x86_64/nux-dextop-release-0-2.el6.nux.noarch.rpm
yum info vlc
yum install vlc

Wednesday, 21 October 2015

Reinstall a corrupted or destroyed boot partition. How to install Adobe Reader on Centos 6

How to install Adobe Reader on Centos 6

yum localinstall http://linuxdownload.adobe.com/linux/i386/AdbeRdr9.5.5-1_i486linux_enu.rpm

or

yum localinstall http://linuxdownload.adobe.com/linux/x86_64/adobe-release-x86_64-1.0-1.noarch.rpm

cannot create key change index database disk image is malformed

#yum clean all

#yum clean metadata

#yum clean dbcache

or

#yum history new

then
#yum makecache

Yum segmentation fault ( core dumped )

#rm -rf /var/lib/rpm/__db.*

#rpm --rebuilddb

#yum clean all

#yum makecache

Scriptlet failed exit status 1

Run the following command

#rpm -e package-name --noscripts

Error : cannot retreive metalink for repository : epel. Please verify its path and try again

#sed -i "s/mirrorlist=https/mirrorlist=http/" /etc/yum.repos.d/epel.repo
#yum check-update

Running these commands will update the repo to use HTTP rather than HTTPS

ftp issue 500: oops : cannot change directory

#getenforce ( Selinux status )
enforcing ( if output)

#getsebool -a | grep ftp

check for ftp_home_dir ---- off
if it is in off state then
#setsebool -P ftp_home_dir 1 ( or on )

hence problem solved

Reinstall a corrupted or destroyed boot partition.

Lately I have had a couple of systems where the boot partition got corrupted or it's contents
deleted mistakenly. Even though I could not boot the system, I did not want to reinstall the whole
system and recover the data from backups.

1. Boot the computer into rescue mode with the relevant CD/DVD by typing "linux rescue" at the boot prompt.
2. Mount the / partition of the system. On CentOS this is automatically done and the / is mounted on /mnt/sysimage.
Otherwise just do (assuming the root partition is on /dev/sda2)

mount /dev/sda2 /mnt/sysimage

3. Chroot into the old root partition since that is where we actually want to make all the changes

chroot /mnt/sysimage

4. If the filesystem labels got deleted up for some reason or they don't agree with what is described in /etc/fstab we should fix that (Assuming the boot partition is /dev/sda1):

e2label /dev/sda1 /boot

5. Make sure the boot partition is mounted:

mount /dev/sda1 /boot

6. Mount the CD-ROM we used to boot the machine

mkdir /media/cdrom
mount -o loop,ro /dev/hdc /media/cdrom

7. Now we need to install the relevant rpms. Make sure you pick the correct kernel for your configuration system (PAE etc..):

cd /media/cdrom/CentOS (this will vary depending on the distro)
rpm -ivh --force kernel-2.6.18-164.el5.i686.rpm
rpm -Uvh --force grub-0.97-13.5.i386.rpm
rpm -Uvh --force redhat-logos-4.9.99-11.el5.centos.noarch.rpm

8. Install GRUB:

grub-install /dev/sda1 (or whichever partition boot is mounted on)

9. If /boot/grub/grub.conf is also lost, you need to create it manually.

vim /boot/grub/grub.conf default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS
        root (hd0,0)
        kernel /vmlinuz-6.18-164.el5 ro root=/dev/VolGroup00/LogVol00
        initrd /initrd-2.6.18-164.el5.img

10. Lastly make a soft link to grub.conf:

cd /boot/grub
ln -s grub.conf menu.lst

Reboot the system and if everything goes well it should boot normally. Run immediately a yum upgrade incase you had to install an older version of the kernel from the CD-ROM.

Wednesday, 12 August 2015

How to Set or Increase Memory Heap Size in Apache Tomcat

By default Tomcat server sets its own memory heap size 64MB but its not

enough for run your application, so we can set size by CATALINA_OPTS or

JAVA_OPTS,

-Xmx set Maximum Java Heap Size
-Xms set Initial Java Heap Size

Option 1:

Open the catalina.sh script file under $CATALINA_HOME/bin/catalina.sh

directory assign it,

export CATALINA_OPTS="-Xms128M -Xmx512M"

or simply export,

export CATALINA_OPTS="-Xms128M -Xmx512MB"

The heap size has been set to Minumum 128MB and maximum 512MB

Option 2:

$CATALINA_HOME/bin/setenv.sh

Another option is create a setenv.sh file and add below line,

export CATALINA_OPTS="${CATALINA_OPTS}
 -Djava.awt.headless=true 
-Dorg.apache.jasper.runtime.BodyContentImpl.LIMIT_BUFFER=true 
-Dmail.mime.decodeparameters=true -Xms128m -Xmx512m -XX:PermSize=256m 
-XX:MaxPermSize=950m -XX:+CMSClassUnloadingEnabled 
-XX:+CMSPermGenSweepingEnabled"

export CATALINA_OPTS="-Xms128M -Xmx512MB"

You might restart tomcat server,

# pkill -9 java

# /usr/local/apache-tomcat/bin/startup.sh

# ps aux | grep java

root      9447  1.1 13.2 2127844 543868 ?      Sl   17:20   3:38 /usr/java/jdk1.7.0/bin/java -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.util.logging.config.file=/usr/local/tomcat7/conf/logging.properties -Djava.awt.headless=true -Dorg.apache.jasper.runtime.BodyContentImpl.LIMIT_BUFFER=true -Dmail.mime.decodeparameters=true -Xms128m -Xmx512m -XX:MaxPermSize=512m -XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled -Djava.endorsed.dirs=/usr/local/tomcat7/endorsed -classpath :/usr/local/tomcat6/bin/bootstrap.jar:/usr/local/tomcat7/bin/commons-logging-api.jar -Dcatalina.base=/usr/local/tomcat7 -Dcatalina.home=/usr/local/tomcat7 -Djava.io.tmpdir=/usr/local/tomcat6/temp org.apache.catalina.startup.Bootstrap start

root     12761  0.0  0.0 103244   868 pts/0    S+   22:24   0:00 grep java

or can use netstat command,

# netstat -anp | grep java

tcp        0      0 :::8009                     :::*                        LISTEN      9447/java           

tcp        0      0 :::8080                     :::*                        LISTEN      9447/java           

tcp        0      0 ::ffff:127.0.0.1:8005       :::*                        LISTEN      9447/java           

tcp        0      0 ::ffff:127.0.0.1:35334      ::ffff:127.0.0.1:3306       ESTABLISHED 9447/java           

tcp        0      0 ::ffff:127.0.0.1:56156      ::ffff:127.0.0.1:3306       ESTABLISHED 9447/java           

unix  2      [ ]         STREAM     CONNECTED     113825 9447/java

Windows Server:

To set in windows operating system, Create a setenv.bat file and add the below line,

export JAVA_OPTS="-server -Xmx512m"

set JAVA_OPTS="-Xms256m -Xmx512m"

Error:

If you may get an error java.lang.OutOfMemoryError: PermGen space in both windows or linux system,

Configure the MaxPermSize value in setenv.sh or catalina.sh like,

export JAVA_OPTS="-Xms256m -Xmx512m -XX:MaxPermSize=128m"

If you have changed any configuration might restart tomcat server.

Friday, 24 July 2015

Webacula Monitoring getting blank page/ How to get the Webacula login page

When you run webacula monitoring :

1.If you get the blank page then check the below command

#psql -h localhost -U postgres -d bacula

the output should be:

psql (9.2.4)

Type "help" for help.

bacula=#

if you get the error like below:

psql: could not connect to server : connection refused.

Is the server running on the localhost and accepting Tcp/Ip connection on port 5432?

Then run the below command

#setsebool -P httpd_can_network_connect 1

And disable selinux:

#cd /etc/sysconfig

#vi selinux

Add the below line and save the file

SELINUX=disabled

#SELINUX=enforcing /* comment this line*/

2.Error: In /etc/httpd/conf.d/errorlog /var/www/html/webacula/data/cache not exists

Solution: #chmod -R 777 /var/www/html/webacula/data/cache

3.Error: httpd could not reliably determine the server's fully qualified domain

Solution: Add the below line in /etc/httpd/conf/httpd.conf

#cd /etc/httpd/conf

#vim httpd.conf

ServerName localhost

And save the file.

Now restart the httpd

#service httpd restart

4.While creating postgresql tables if you get the error like below

role “root” does not exist

Then

#su – postgres

#psql

#CREATE ROLE root;

#ALTER ROLE root LOGIN;

Now create postgresql tables.

5.Check the webacula tables

#su – postgres

#psql

#\c bacula

Owner of webacula tables should be postgres otherwise change it.

#ALTER TABLE <table name> OWNER TO postgres;

like this do for all tables.

httpd could not reliably determine the server's fully qualified domain

Error: httpd could not reliably determine the server's fully qualified domain

Solution: Add the below line in /etc/httpd/conf/httpd.conf

#cd /etc/httpd/conf

#vim httpd.conf

ServerName localhost

And save the file.

Now restart the httpd

#service httpd restart

How to upgrade firefox on centos6/Rhel/Fedora

Download repo:

#wget  http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm

#rpm -Uvh epel-release-6-8.noarch.rpm

#wget http://rpms.famillecollet.com/enterprise/remi-release-6.rpm

#rpm -Uvh remi-release-6.rpm

#yum --enablerepo=remi list firefox

#yum --enablerepo=remi install firefox

#firefox

#cd /usr/local

Download firefox 36:

#wget http://ftp.mozilla.org/pub/mozilla.org/firefox/releases/36.0.1/linux-x86_64/en-US/firefox-36.0.1.tar.bz2

#tar xvjf firefox-36.0.1.tar.bz2

#ln -s /usr/local/firefox/firefox /usr/bin/firefox

#firefox &

nmap

#nmap machin_name

unexpectedly disconnected from boot status daemon init: prefdm respawning too fast,stopped

Installing boot loader only using grub:in rescue installed system centos 6/Rhel/Fedora

# grub

Probing devices to guess BIOS drives. This may take a long time.

GNU GRUB version 0.97 (640K lower / 3072K upper memory)

[ Minimal BASH-like line editing is supported. For the first word, TAB

lists possible command completions. Anywhere else TAB lists the possible

completions of a device/filename.]

grub> find /boot/grub/stage1

(hd0,5)

(hd0,9)

grub> root (hd0,5)

Filesystem type is ext2fs, partition type 0x83

grub> setup (hd0)

Checking if "/boot/grub/stage1" exists... yes

Checking if "/boot/grub/stage2" exists... yes

Checking if "/boot/grub/e2fs_stage1_5" exists... yes

Running "embed /boot/grub/e2fs_stage1_5 (hd0)"... 15 sectors are embedded.

Succeeded

Running "install /boot/grub/stage1 (hd0) (hd0)1+15 p

(hd0,5)/boot/grub/stage2

/boot/grub/grub.conf"... succeeded

Done.

grub> quit

#reboot

hence problem solved.

Installing Grub using grub-install: in rescue installed system centos 6/Rhel/Fedora

#df -h

check the filesystem name of /boot

#cd /sbin

#grub-install /dev/sda5 /* where /dev/sda5 is /boot filesystem name*/

output:

Installation finished. No error reported.

This is the contents of the device map /boot/grub/device.map.

Check if this is correct or not. If any of the lines is incorrect,

fix it and re-run the script `grub-install'.

# this device map was generated by anaconda

(hd0) /dev/sda

#reboot

How to upgrade centos 6.2 to centos 6.5

Upgrade an existing system:

Insert centos 6.5 DVD
Press F10
Select Install or upgrade an existing system
skip
Next
English Next
U.S English Next
Select Basic storage devices Next
Select upgrade an existing system Next
Select Create a new bootloader Next
Select centos 6.5 Install

Hence problem solved

After this if you didn't get GUI then

#vi /etc/inittab

Replace 3 with 5 in the last line id:5

#reboot

now you will get the gui

If you feel the desktop is different from the desktop before you used then follow below steps

#vim /etc/sysconfig/desktop

DESKTOP=GNOME

DISPLAYMANAGER=GNOME

#reboot

Description about display manager

There is a configuration file called /etc/sysconfig/desktop. This file defines default display manager and desktop name.

Display manager can be any one of the following:
[a] gnome (gdm)
[b] kde (kdm)
[c] xdm (xdm)

Desktop can be any one of the following
[a] KDE
[b] GNOME
[c] XFCE

Specifying GNOME as a display manager will invoke GDM.

Upon boot, the system will run /etc/init/prefdm.conf which will in turn call the "Preferred Display Manager" (prefdm) script /etc/X11/prefdm which will utilize the settings in /etc/sysconfig/desktop if available.

Errors And Fixes While booting

When I start the centos 6.2 system centos6 logo stucked it didn't give the login prompt

So, I restart the system by CTRL+ALT+DELETE and i pressed the ESC key when circle had come

to see the errors.

The errors are:

unexpectedly disconnected from boot status daemon
init: prefdm respawning too fast,stopped

In my system may be These errors are because httpd remove/update.

Before this I did following:

I removed httpd by #yum remove httpd*

after that I installed httpd-2.4.10 source file by following some steps.

After i reboot the system i got the above errors.

There are two ways to fix these errors:

by rescue installed system from centos 6.2 dvd
by upgrade an existing system from centos 6.5 dvd

Rescue installed system:

Insert centos 6.2 dvd
press F10 key
select cd/dvd sta
select rescue installed system
Language English OK
US OK
Drive Local cd/dvd OK
Enable network interface OK
Configure network IPv4 settings manually by giving IP address,Gateway and Nameserver
after that press OK until you get command line prompt like bash4.1$
$chroot /mnt/sysimage
#yum remove httpd*
you have to install httpd-2.2.15-29.el6.centos.x86_64
Download following rpm packages in another linux system
httpd-2.2.15-29.el6.centos.x86_64.rpm
httpd-devel-2.2.15-29.el6.centos.x86_64.rpm
httpd-tools-2.2.15-29.el6.centos.x86_64.rpm
In that goto downloads copy the above three files to one folder and copy that folder to Desktop
compress the folder to .zip(httpd.zip)
now open terminal
#cd /root/Desktop
ftp 192.168.1.22 /*your system ip address*/
ftp>cd /root
ftp>bin
ftp>hash
ftp>prompt
ftp>mput httpd.zip
ftp>bye
now from your system #cd /root
#unzip httpd.zip
#rpm -ivh httpd-2.2.15-29.el6.centos.x86_64.rpm
#rpm -ivh httpd-devel-2.2.15-29.el6.centos.x86_64.rpm
#rpm -ivh httpd-tools-2.2.15-29.el6.centos.x86_64.rpm
#sync
#exit
#reboot

hence problem solved

PostgreSQL+OpenLDAP+CentOS

$ yum install postgresql-* openldap-servers-sql openldap-clients

$ su - postgres

$ initdb -D /var/lib/pgsql/data

$ postmaster -D /var/lib/pgsql/data &

$ exit

$ cat /etc/odbc.ini

[ODBC Data Sources]

PgSQL=PostgreSQL

[PgSQL]

Driver=/usr/lib/psqlodbc.so

Description=Connection to LDAP/Postgresql

Servername=localhost

Port=5432

Protocol=6.4

FetchBufferSiza=99

Username=test

Password=test

Database=pg_ldap

ReadOnly=no

Debug=1

CommLog=1

[ODBC]

InstallDir=/usr/lib/

$ cat /etc/odbcinst.ini

[PostgreSQL]

Description = ODBC for PostgreSQL

Driver = /usr/lib/psqlodbc.so

FileUsage = 1

$ cd /usr/share/doc/openldap-servers-sql-2.3.43/rdbms_depend/pgsql

$ cp * /var/lib/pgsql/data

$ cat /etc/openldap/slapd.conf

include /etc/openldap/schema/core.schema

include /etc/openldap/schema/cosine.schema

include /etc/openldap/schema/inetorgperson.schema

include /etc/openldap/schema/misc.schema

include /etc/openldap/schema/nis.schema

include /etc/openldap/schema/openldap.schema

include /etc/openldap/schema/samba.schema

access to *

by self write

by * read

access to * by dn="cn=root,dc=example,dc=com" write

pidfile /var/run/openldap/slapd.pid

argsfile /var/run/openldap/slapd.args

modulepath /usr/lib/openldap

moduleload back_sql.la

database sql

suffix "dc=example,dc=com"

rootdn "cn=root,dc=example,dc=com"

rootpw secret

dbname PgSQL

dbuser test

dbpasswd test

insentry_query "insert into ldap_entries (id,dn,oc_map_id,parent,keyval) values ((select max(id)+1 from ldap_entries),?,?,?,?)"

upper_func "upper"

strcast_func "text"

concat_pattern "?||?"

has_ldapinfo_dn_ru no

lastmod off

$ su - postgres

$ cd /var/lib/pgsql/data

$ createdb pg_ldap

$ createuser --no-createdb --no-createrole --no-adduser --password test

$ psql -d pg_ldap < backsql_create.sql

$ psql -d pg_ldap < testdb_create.sql

$ psql -d pg_ldap < testdb_metadata.sql

$ psql -d pg_ldap < testdb_data.sql

$psql -d pg_ldap -c "GRANT ALL ON ldap_attr_mappings,ldap_entries,ldap_entry_objclasses,ldap_oc_mappings,referrals,certs TO test1;"

$psql -d pg_ldap -c "GRANT ALL ON ldap_attr_mappings_id_seq,ldap_entries_id_seq,ldap_oc_mappings_id_seq,referrals_id_seq TO test1;"

$psql -d pg_ldap -c "GRANT ALL ON authors_docs,documents,institutes,persons,phones TO test1;"

$ psql -d pg_ldap -c "GRANT ALL ON documents_id_seq,institutes_id_seq,persons_id_seq,phones_id_seq TO test1;"

$ exit

$ /etc/init.d/ldap start

$ ldapsearch -x -h localhost -b "dc=example,dc=com" "(objectClass=*)"

$ echo ‘dn: cn=Test Entry,dc=example,dc=com

objectClass: inetOrgPerson

cn: Test Entry

sn: Entry

givenName: Test’>1.ldif

$ ldapadd -x -h localhost -D “cn=root,dc=example,dc=com” -w secret -f 1.ldif

Thursday, 23 July 2015

How to Install uPortal 4+Postgresql+Centos6/Rhel/Fedora

Uportal Installation and Configuration

Download uPortal 4.2 from the below link:

wget https://s3.amazonaws.com/github-cloud/releases/2614085/812fae44-9031-11e4-871c-020fc24b0d82.gz?response-content-disposition=attachment%3B%20filename%3DuPortal-4.2.0-M1.tar.gz&response-content-type=application/octet-stream&AWSAccessKeyId=AKIAISTNZFOVBIJMK3TQ&Expires=1428645472&Signature=YBB4bTOsxoo3h%2FQr8C%2BZ43hmitI%3D

uPortal Dependencies:

apache-ant-1.8.2
Centos 6.5
apache-maven-3.0.5
apache-tomcat-7.0.59
Java 7
Postgresql

Download links:

ant:

wget http://archive.apache.org/dist/ant/binaries/apache-ant-1.8.2-bin.tar.gz

maven:

wget http://www.apache.org/dist/maven/binaries/apache-maven-3.0.5-bin.tar.gz

tomcat:

wget http://ftp.wayne.edu/apache/tomcat/tomcat-7/v7.0.59/bin/apache-tomcat-7.0.59.tar.gz

#cp /root/Downloads/apache-ant-1.8.2-bin.tar.gz /opt/uportal_dep

#cp /root/Downloads/apache-maven-3.0.5-bin.tar.gz /opt/uportal_dep

#cp /root/Downloads/apache-tomcat-7.0.59.tar.gz /usr/local

#cd /usr/local

#mv apache-tomcat-7.0.59 uPortal_tomcat

#vim ~/.bashrc

add below lines:

export ANT_HOME=/opt/uportal_dep/apache-ant-1.8.2

export M2_HOME=/opt/uportal_dep/apache-maven-3.0.5

export M2=$M2_HOME/bin

export PATH=$M2:$PATH

export JAVA_HOME=/usr

export TOMCAT_HOME=/usr/local/uPortal_tomcat

and save it by :wq

#source ~/.bashrc

#vim /usr/local/uPortal_tomcat/conf/catalina.properties

add

shared.loader=${catalina.base}/shared/lib/*.jar

and save it by :wq

#vim /usr/local/uPortal_tomcat/bin/setenv.sh

export JAVA_OPTS="$JAVA_OPTS -XX:+PrintCommandLineFlags -XX:MaxPermSize=384m -Xms1024m -Xmx1024m -Djsse.enableSNIExtension=false"

and save it by :wq

#vim /usr/local/uPortal_tomcat/bin/startup.sh

export CATALINA_OPTS=”-Xms512M -Xmx1024M”

and save it by :wq

#su – postgres

$psql

=#create database uportal;

=#create user uportal with password 'uportal';

=#grant all privileges on database uportal to uportal;

=#\q

$exit

#cd /opt

#cp /root/Downloads/uPortal-4.2.0-M1.tar.gz /opt

#tar -zxvf uPortal-4.2.0-M1.tar.gz

#cd uPortal-4.2.0-M1

#cd uportal-db

#vim pom.xml

uncomment postgresql dependency

if your postgresql is below 9.2 version then it should be

<groupId>postgresql</groupId>

<artifactId>postgresql</artifactId>

<scope>compile</scope>

</dependency>

if your postgresql is 9.2 later then it should be

<groupId>org.postgresql</groupId>

<artifactId>postgresql</artifactId>

<scope>compile</scope>

</dependency>

#cd /opt/uPortal-4.2.0-M1/filters

#vim local.properties

comment hsql lines

add postgresql below lines

## Database Connection Settings (Uncomment the Maven Filters section in rdbm.properties)

environment.build.hibernate.connection.driver_class=org.postgresql.Driver

environment.build.hibernate.connection.url=jdbc:postgresql://localhost:5432/uportal

environment.build.hibernate.connection.username=uportal

environment.build.hibernate.connection.password=uportal

environment.build.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect

environment.build.hibernate.connection.validationQuery=select 1

and save it by :wq

#cd /opt/ uPortal-4.2.0-M1

#cp build.properties.sample build.properties

add

server.home=/usr/local/uPortal_tomcat

and save it by :wq

#cd /opt/uPortal-4.2.0-M1

#ant dbtest > antdbtest.log &

#tail -f antdbtest.log

After getting build successful

#ant clean initportal > antinit.log &

After getting build successful

Restart Tomcat as below

#cd /usr/local/uPortal_tomcat

#cd bin

#./shutdown.sh

check whether tomcat process is running or not by

#ps -efa | grep tomcat

check whether any process is running at port 8080 by

#netstat -tlnp | grep '8080'

#./startup.sh

open the web browser and check

localhost:8080/uPortal

references:

https://wiki.jasig.org/display/UPM41/Installing+uPortal