Category Archives: centos6

[DEPRECATED] CentOS 6: Install WSO2 Data Services Server

Versions

CentOS 6.3
Oracle Java JDK 1.6
WSO2 Data Services Server 3.0.1

Prerequisties

Install Oracle JDK

Install

1. Download
Download Data Services Server from WSO2 website: http://wso2.com/products/data-services-server/
Note: can’t link directly since currently requires filling out a form to download.

2. Extract

unzip wso2dss-3.0.1.zip

1	unzip wso2dss-3.0.1.zip

Note: update version as required
2. Move

sudo mv wso2dss-3.0.1 /usr/lib
sudo ln -s /usr/lib/wso2dss-3.0.1 /usr/lib/wso2dss

1 2	sudo mv wso2dss-3.0.1 /usr/lib sudo ln -s /usr/lib/wso2dss-3.0.1 /usr/lib/wso2dss

Configure

1. Create wso2 user if missing

sudo useradd --system --user-group wso2

1	sudo useradd --system --user-group wso2

2. Update permissions

sudo chown -R wso2:wso2 /usr/lib/wso2dss-3.0.1
sudo chown wso2:wso2 /usr/lib/wso2dss

1 2	sudo chown -R wso2:wso2 /usr/lib/wso2dss-3.0.1 sudo chown wso2:wso2 /usr/lib/wso2dss

3. Create service script /etc/init.d/wso2dss

#!/bin/sh
#
# chkconfig: 2345 80 80
#
# Bash script to run wso2server.sh as a service
#

# Note: Normal env variables are discarded by service. So must export JAVA_HOME here, see http://serverfault.com/questions/374404/service-command-and-environment-variables
export JAVA_HOME=/usr/java/latest

WSO2_HOME=/usr/lib/wso2dss
WSO2_DAEMON=bin/wso2server.sh
WSO2_USER=wso2
START_OPTIONS=start
STOP_OPTIONS=stop

start() {
    echo "Starting WSO2 Data Services Server..."
    su --preserve-environment $WSO2_USER -c "cd $WSO2_HOME && $WSO2_DAEMON $START_OPTIONS"
    return 0
}

stop() {
    echo "Stopping WSO2 Data Services Server..."
    su --preserve-environment $WSO2_USER -c "cd $WSO2_HOME && $WSO2_DAEMON $STOP_OPTIONS"
    return 0
}

case "$1" in
  start)
    start
    ;;
  stop)
    stop
      ;;
  restart)
    stop
    start
    ;;
  *)
  echo $"Usage: $0 {start|stop|restart}"
  exit 1
esac

exit $?

#!/bin/sh

# chkconfig: 2345 80 80

# Bash script to run wso2server.sh as a service

# Note: Normal env variables are discarded by service. So must export JAVA_HOME here, see http://serverfault.com/questions/374404/service-command-and-environment-variables

export JAVA_HOME=/usr/java/latest

WSO2_HOME=/usr/lib/wso2dss

WSO2_DAEMON=bin/wso2server.sh

WSO2_USER=wso2

START_OPTIONS=start

STOP_OPTIONS=stop

start() {

echo "Starting WSO2 Data Services Server..."

su --preserve-environment $WSO2_USER -c "cd $WSO2_HOME && $WSO2_DAEMON $START_OPTIONS"

return 0

}

stop() {

echo "Stopping WSO2 Data Services Server..."

su --preserve-environment $WSO2_USER -c "cd $WSO2_HOME && $WSO2_DAEMON $STOP_OPTIONS"

return 0

}

case "$1" in

start)

start

;;

stop)

stop

;;

restart)

stop

start

;;

echo $"Usage: $0 {start|stop|restart}"

exit 1

esac

exit $?

Note: the script hard codes JAVA_HOME, but this can be deferred to the /etc/sysconfig/wso2<product> script (which you must create) if desired. Note that the normal /etc/profile.sh is *not* run for system accounts.
TODO: find better way of setting JAVA_HOME, can’t execute /etc/profile or /etc/profile.d/java.sh directly

4. Make it executable

sudo chmod +x /etc/init.d/wso2dss

1	sudo chmod +x /etc/init.d/wso2dss

5. Start service

sudo service wso2dss start

1	sudo service wso2dss start

6. Start service on boot

sudo chkconfig wso2dss on

1	sudo chkconfig wso2dss on

7. Open the following ports as required:

9443 – carbon admin and https port used to access data services
9763 – http port used to access data services

See Open a port for iptables

Verify

Watch wso2dss logs:

sudo tail -F /usr/lib/wso2dss/repository/logs/wso2carbon.log

1	sudo tail -F /usr/lib/wso2dss/repository/logs/wso2carbon.log

Should see the following:

...
TID: [0] [DSS] [2013-03-29 11:04:23,272]  INFO {org.wso2.carbon.core.internal.permission.update.PermissionUpdater} -  Permission cache updated for tenant -1234 {org.wso2.carbon.core.internal.permission.update.PermissionUpdater}
TID: [0] [DSS] [2013-03-29 11:04:25,293]  INFO {org.wso2.carbon.core.transports.http.HttpsTransportListener} -  HTTPS port       : 9443 {org.wso2.carbon.core.transports.http.HttpsTransportListener}
TID: [0] [DSS] [2013-03-29 11:04:25,293]  INFO {org.wso2.carbon.core.transports.http.HttpTransportListener} -  HTTP port        : 9763 {org.wso2.carbon.core.transports.http.HttpTransportListener}
TID: [0] [DSS] [2013-03-29 11:04:26,587]  INFO {org.wso2.carbon.core.init.JMXServerManager} -  JMX Service URL  : service:jmx:rmi://localhost:11111/jndi/rmi://localhost:9999/jmxrmi {org.wso2.carbon.core.init.JMXServerManager}
TID: [0] [DSS] [2013-03-29 11:04:26,618]  INFO {org.wso2.carbon.core.internal.StartupFinalizerServiceComponent} -  Server           :  WSO2 Data Services Server-3.0.1 {org.wso2.carbon.core.internal.StartupFinalizerServiceComponent}
TID: [0] [DSS] [2013-03-29 11:04:26,618]  INFO {org.wso2.carbon.core.internal.StartupFinalizerServiceComponent} -  WSO2 Carbon started in 23 sec {org.wso2.carbon.core.internal.StartupFinalizerServiceComponent}
TID: [0] [DSS] [2013-03-29 11:04:26,975]  INFO {org.wso2.carbon.ui.internal.CarbonUIServiceComponent} -  Mgt Console URL  : https://10.50.76.30:9443/carbon/ {org.wso2.carbon.ui.internal.CarbonUIServiceComponent}

...

TID: [0] [DSS] [2013-03-29 11:04:23,272] INFO {org.wso2.carbon.core.internal.permission.update.PermissionUpdater} - Permission cache updated for tenant -1234 {org.wso2.carbon.core.internal.permission.update.PermissionUpdater}

TID: [0] [DSS] [2013-03-29 11:04:25,293] INFO {org.wso2.carbon.core.transports.http.HttpsTransportListener} - HTTPS port : 9443 {org.wso2.carbon.core.transports.http.HttpsTransportListener}

TID: [0] [DSS] [2013-03-29 11:04:25,293] INFO {org.wso2.carbon.core.transports.http.HttpTransportListener} - HTTP port : 9763 {org.wso2.carbon.core.transports.http.HttpTransportListener}

TID: [0] [DSS] [2013-03-29 11:04:26,587] INFO {org.wso2.carbon.core.init.JMXServerManager} - JMX Service URL : service:jmx:rmi://localhost:11111/jndi/rmi://localhost:9999/jmxrmi {org.wso2.carbon.core.init.JMXServerManager}

TID: [0] [DSS] [2013-03-29 11:04:26,618] INFO {org.wso2.carbon.core.internal.StartupFinalizerServiceComponent} - Server : WSO2 Data Services Server-3.0.1 {org.wso2.carbon.core.internal.StartupFinalizerServiceComponent}

TID: [0] [DSS] [2013-03-29 11:04:26,618] INFO {org.wso2.carbon.core.internal.StartupFinalizerServiceComponent} - WSO2 Carbon started in 23 sec {org.wso2.carbon.core.internal.StartupFinalizerServiceComponent}

TID: [0] [DSS] [2013-03-29 11:04:26,975] INFO {org.wso2.carbon.ui.internal.CarbonUIServiceComponent} - Mgt Console URL : https://10.50.76.30:9443/carbon/ {org.wso2.carbon.ui.internal.CarbonUIServiceComponent}

Visit your new Carbon website: https://<hostname>:9443/carbon/

Initial login:

Username: admin
Password: admin

Important Note: if are you going to want to configure API Manager to use LDAP for logins, don’t log in using the default admin account!

[DEPRECATED] CentOS 6: Install WSO2 API Manager

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Versions

CentOS 6.3
Oracle Java JDK 1.6
WSO2 API Manager 1.3.1

Prerequisties

Install

1. Download
Download API Manager from WSO2 website: http://wso2.com/products/api-manager/
Note: can’t link directly since currently requires filling out a form to download.
2. Extract

unzip wso2am-1.3.1.zip

1	unzip wso2am-1.3.1.zip

Note: update version as required

2. Move

sudo mv wso2am-1.3.1 /usr/lib
sudo ln -s /usr/lib/wso2am /usr/lib/wso2am

1 2	sudo mv wso2am-1.3.1 /usr/lib sudo ln -s /usr/lib/wso2am /usr/lib/wso2am

Configure

1. Create wso2 user if missing

sudo useradd --system --user-group wso2

1	sudo useradd --system --user-group wso2

2. Update permissions

sudo chown -R wso2:wso2 /usr/lib/wso2am-1.3.1

1	sudo chown -R wso2:wso2 /usr/lib/wso2am-1.3.1

3. Create service script /etc/init.d/wso2am

#!/bin/sh
#
# chkconfig: 2345 80 80
#
# Bash script to run wso2server.sh as a service
#

# Note: Normal env variables are discarded by service. So must export JAVA_HOME here, see http://serverfault.com/questions/374404/service-command-and-environment-variables
export JAVA_HOME=/usr/java/latest

WSO2_HOME=/usr/lib/wso2am
WSO2_DAEMON=bin/wso2server.sh
WSO2_USER=wso2
START_OPTIONS=start
STOP_OPTIONS=stop

start() {
    echo "Starting WSO2 API Manager..."
    su --preserve-environment $WSO2_USER -c "cd $WSO2_HOME && $WSO2_DAEMON $START_OPTIONS"
    return 0
}

stop() {
    echo "Stopping WSO2 API Manager..."
    su --preserve-environment $WSO2_USER -c "cd $WSO2_HOME && $WSO2_DAEMON $STOP_OPTIONS"
    return 0
}

case "$1" in
  start)
    start
    ;;
  stop)
    stop
      ;;
  restart)
    stop
    start
    ;;
  *)
  echo $"Usage: $0 {start|stop|restart}"
  exit 1
esac

exit $?

#!/bin/sh

# chkconfig: 2345 80 80

# Bash script to run wso2server.sh as a service

# Note: Normal env variables are discarded by service. So must export JAVA_HOME here, see http://serverfault.com/questions/374404/service-command-and-environment-variables

export JAVA_HOME=/usr/java/latest

WSO2_HOME=/usr/lib/wso2am

WSO2_DAEMON=bin/wso2server.sh

WSO2_USER=wso2

START_OPTIONS=start

STOP_OPTIONS=stop

start() {

echo "Starting WSO2 API Manager..."

su --preserve-environment $WSO2_USER -c "cd $WSO2_HOME && $WSO2_DAEMON $START_OPTIONS"

return 0

}

stop() {

echo "Stopping WSO2 API Manager..."

su --preserve-environment $WSO2_USER -c "cd $WSO2_HOME && $WSO2_DAEMON $STOP_OPTIONS"

return 0

}

case "$1" in

start)

start

;;

stop)

stop

;;

restart)

stop

start

;;

echo $"Usage: $0 {start|stop|restart}"

exit 1

esac

exit $?

Note: the script hard codes JAVA_HOME, but this can be deferred to the /etc/sysconfig/wso2am script (which you must create) if desired. Note that the normal /etc/profile.sh is *not* run for system accounts.
TODO: find better way of setting JAVA_HOME, can’t execute /etc/profile or /etc/profile.d/java.sh directly

4. Make it executable

sudo chmod +x /etc/init.d/wso2am

1	sudo chmod +x /etc/init.d/wso2am

5. Start service

sudo service wso2am start

1	sudo service wso2am start

6. Start service on boot

sudo chkconfig wso2am on

1	sudo chkconfig wso2am on

7. Open the following ports as required:

9443 – carbon admin, publisher and store applications
8243 – http port used by gateway to access API services
8280 – https port used by gateway to access API services

See Open a port for iptables

Verify

Watch wso2dss logs:

sudo tail -F /usr/lib/wso2am/repository/logs/wso2carbon.log

1	sudo tail -F /usr/lib/wso2am/repository/logs/wso2carbon.log

Should see the following:

...

...

Visit your new Carbon website: https://XXX.XXX.XXX.XXX:9443/carbon/

Initial login:

Username: admin
Password: admin

Configure LDAP

See Configure WSO2 to use LDAP

CentOS 6: Install Shutter a screen capture program

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Versions

CentOS 6.5

Prerequisites

CentOS 6: Install EPEL yum repository

Install

sudo yum localinstall http://li.nux.ro/download/nux/dextop/el6/x86_64/nux-dextop-release-0-2.el6.nux.noarch.rpm
sudo yum install shutter

1 2	sudo yum localinstall http://li.nux.ro/download/nux/dextop/el6/x86_64/nux-dextop-release-0-2.el6.nux.noarch.rpm sudo yum install shutter

Start

$ shutter

$ shutter

CentOS 6: Install IntelliJ IDEA

2 Replies

Versions

CentOS 6.5 x86_64
Oracle Java JDK 1.7
IntelliJ IDEA Community 13.1.4

Prerequisties

Install

Note	replace $VERSION below with the latest version of IntelliJ IDEA. After extraction, replace $BUILD with the build number located on the directory named idea-IC-$BUILD.

Download latest version of IntelliJ IDEA, extract and put in /usr/lib (file names vary with version number):

wget http://download.jetbrains.com/idea/ideaIC-$VERSION.tar.gz
tar xvf ideaIC-$VERSION.tar.gz
sudo mv idea-IC-$BUILD /usr/lib
sudo ln -sf /usr/lib/idea-IC-$BUILD /usr/lib/idea

wget http://download.jetbrains.com/idea/ideaIC-$VERSION.tar.gz

tar xvf ideaIC-$VERSION.tar.gz

sudo mv idea-IC-$BUILD /usr/lib

sudo ln -sf /usr/lib/idea-IC-$BUILD /usr/lib/idea

Example

wget http://download.jetbrains.com/idea/ideaIC-13.1.4.tar.gz
tar xvf ideaIC-13.1.4.tar.gz
sudo mv idea-IC-135.1230 /usr/lib
sudo ln -sf /usr/lib/idea-IC-135.1230 /usr/lib/idea

wget http://download.jetbrains.com/idea/ideaIC-13.1.4.tar.gz

tar xvf ideaIC-13.1.4.tar.gz

sudo mv idea-IC-135.1230 /usr/lib

sudo ln -sf /usr/lib/idea-IC-135.1230 /usr/lib/idea

Configure

Add to /usr/bin:

Shell

sudo ln -sf /usr/lib/idea/bin/idea.sh /usr/bin/idea

1

sudo ln -sf /usr/lib/idea/bin/idea.sh /usr/bin/idea

Typically, I need more memory for the JVM that runs IntelliJ IDEA. Edit /usr/lib/idea/bin/idea.vmoptions and change the following lines:

Default

... -Xms2048m -Xmx2048m -XX:MaxPermSize=512m -XX:ReservedCodeCacheSize=128m ...

1
2
3
4
5
6

...
-Xms2048m
-Xmx2048m
-XX:MaxPermSize=512m
-XX:ReservedCodeCacheSize=128m
...

Repeat the same edits above for /usr/lib/idea/bin/idea64.vmoptions
Raise the inotify limit of watchable directories from 7k to a higher value, such as 512k, edit /etc/sysctl.conf

Default

fs.inotify.max_user_watches = 524288

1

fs.inotify.max_user_watches = 524288

Apply the change without reboot:

Default

sudo sysctl -p

1

sudo sysctl -p

Verify

Start it up:

$ idea

$ idea

Sources

http://confluence.jetbrains.com/display/IDEADEV/Inotify+Watches+Limit

[DEPRECATED] CentOS 6: Install Apache Cassandra using Datastax

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Versions

CentOS 6.3
Oracle Java JDK 1.6
Note: if running with WSO2 Data Services Server 3.0.1, only Apache Cassandra 1.1 is supported
Apache Cassandra 1.2.3 or 1.1.9
JNA 3.5.1

Prerequisites

WARNING: Cassandra will fail with no or an erroneous error message if run with openjdk 1.6!
Install Oracle JDK

Install

1. Edit /etc/yum.repos.d/datastax.repo

[datastax]
name= DataStax Repo for Apache Cassandra
baseurl=http://rpm.datastax.com/community
enabled=1
gpgcheck=0

[datastax]

name= DataStax Repo for Apache Cassandra

baseurl=http://rpm.datastax.com/community

enabled=1

gpgcheck=0

2. Install Cassandra

For Apache Cassandra 1.2.3:

sudo yum install cassandra12

1	sudo yum install cassandra12

For Apache Cassandra 1.1.9:

sudo yum install apache-cassandra11

1	sudo yum install apache-cassandra11

3. Install a copy of JNA jar just for Cassandra
Note: JNA from base repo is 3.2.4 while Cassandra requires 3.2.7+

cd /usr/share/cassandra/lib
sudo wget https://maven.java.net/content/repositories/releases/net/java/dev/jna/jna/3.5.1/jna-3.5.1.jar
sudo chown cassandra:cassandra jna-3.5.1.jar
sudo chown 755 jna-3.5.1.jar

cd /usr/share/cassandra/lib

sudo wget https://maven.java.net/content/repositories/releases/net/java/dev/jna/jna/3.5.1/jna-3.5.1.jar

sudo chown cassandra:cassandra jna-3.5.1.jar

sudo chown 755 jna-3.5.1.jar

4. Fix permissions

sudo chown -R cassandra:cassandra /var/lib/cassandra
sudo chown -R cassandra:cassandra /var/log/cassandra

1 2	sudo chown -R cassandra:cassandra /var/lib/cassandra sudo chown -R cassandra:cassandra /var/log/cassandra

Configure

1. Edit /etc/profile.d/cassandra.sh

export CASSANDRA_HOME=/usr/share/cassandra

1	export CASSANDRA_HOME=/usr/share/cassandra

2. Load into current session:

source /etc/profile.d/cassandra.sh

1	source /etc/profile.d/cassandra.sh

3. Edit the following settings in /etc/cassandra/conf/cassandra.yaml:

cluster_name: '<your cluster name>'
...
          - seeds: "<first node hostname or ip>"
...
listen_address: <hostname or ip>
...
rpc_address: 0.0.0.0

cluster_name: '<your cluster name>'

...

- seeds: "<first node hostname or ip>"

...

listen_address: <hostname or ip>

...

rpc_address: 0.0.0.0

Note: for more details about configuring and optimizing a multi-node cluster, see sources.

Example:

cluster_name: 'Lances Cassandra Cluster'
...
          - seeds: "192.168.0.1"
...
listen_address: 192.168.0.1
...
rpc_address: 0.0.0.0

cluster_name: 'Lances Cassandra Cluster'

...

- seeds: "192.168.0.1"

...

listen_address: 192.168.0.1

...

rpc_address: 0.0.0.0

4. Open ports

7199 for JMX
9160 for Cassandra Thrift
7000 for Cassandra Gossip

See Open a port for iptables

5. Start cassandra:

sudo service cassandra start

1	sudo service cassandra start

6. Start cassandra on boot:

sudo chkconfig cassandra on

1	sudo chkconfig cassandra on

Test

Test First Node

Note: only use this test on the first node of the cluster

cassandra-cli

1	cassandra-cli

Enter at cassandra-cli:

create keyspace TEST;
use TEST;
create column family Users with key_validation_class = 'UTF8Type' and comparator = 'UTF8Type' and default_validation_class = 'UTF8Type';
set Users[1234][name] = lance;
set Users[1234][password] = password;
get Users[1234];

create keyspace TEST;

use TEST;

create column family Users with key_validation_class = 'UTF8Type' and comparator = 'UTF8Type' and default_validation_class = 'UTF8Type';

set Users[1234][name] = lance;

set Users[1234][password] = password;

get Users[1234];

Verify:

=> (column=name, value=lance, timestamp=1364348576638000)
=> (column=password, value=password, timestamp=1364348576659000)
Returned 2 results.
Elapsed time: 33 msec(s).

=> (column=name, value=lance, timestamp=1364348576638000)

=> (column=password, value=password, timestamp=1364348576659000)

Returned 2 results.

Elapsed time: 33 msec(s).

Test Other Nodes

nodetool ring

1	nodetool ring

Output:

Address         DC          Rack        Status State   Load            Effective-Ownership Token                                       
                                                                                           56249068152829558755232038006353068538      
XXX.XXX.XXX.XXX     datacenter1 rack1       Up     Normal  245.69 KB       77.37%              17740317962663376050438259070624145933      
XXX.XXX.XXX.XXX     datacenter1 rack1       Up     Normal  50.42 KB        22.63%              56249068152829558755232038006353068538

Address DC Rack Status State Load Effective-Ownership Token

56249068152829558755232038006353068538

XXX.XXX.XXX.XXX datacenter1 rack1 Up Normal 245.69 KB 77.37% 17740317962663376050438259070624145933

XXX.XXX.XXX.XXX datacenter1 rack1 Up Normal 50.42 KB 22.63% 56249068152829558755232038006353068538

See Open a port for iptables

Sources

CentOS 6: Install EPEL yum repository

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Versions

CentOS 6.5
EPEL 6.8

Install

Note

replace $MAJOR and $MINOR with the desired major and minor release. as of this writing it is 6 & 8

wget http://dl.fedoraproject.org/pub/epel/$MAJOR/x86_64/epel-release-$MAJOR-$MINOR.noarch.rpm
sudo yum localinstall epel-release-$MAJOR-$MINOR.noarch.rpm

1 2	wget http://dl.fedoraproject.org/pub/epel/$MAJOR/x86_64/epel-release-$MAJOR-$MINOR.noarch.rpm sudo yum localinstall epel-release-$MAJOR-$MINOR.noarch.rpm

wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
sudo yum localinstall epel-release-6-8.noarch.rpm

1 2	wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm sudo yum localinstall epel-release-6-8.noarch.rpm

To discover latest major/minor, visit: http://dl.fedoraproject.org/pub/epel

Verify

$ head /etc/yum.repos.d/epel.repo
[epel]
name=Extra Packages for Enterprise Linux 6 - $basearch
...

$ head /etc/yum.repos.d/epel.repo

[epel]

name=Extra Packages for Enterprise Linux 6 - $basearch

...

CentOS 6: Install ntp to syncronize system time and date

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Versions

CentOS 6.3

Install

sudo yum install ntp

1	sudo yum install ntp

Configure

Syncronize:

sudo ntpdate pool.ntp.org

1	sudo ntpdate pool.ntp.org

Start:

sudo service ntpd start

1	sudo service ntpd start

Start service on boot:

sudo chkconfig ntpd on

1	sudo chkconfig ntpd on

Verify

date

date

Ensure matches current time.

[DEPRECATED] CentOS 6: Install Chrome

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Versions

CentOS 6.3

Install

Edit /etc/yum.repos.d/google-chrome.repo

[google-chrome]
name=google-chrome - 64-bit
baseurl=http://dl.google.com/linux/chrome/rpm/stable/x86_64
enabled=1
gpgcheck=1
gpgkey=https://dl-ssl.google.com/linux/linux_signing_key.pub

[google-chrome]

name=google-chrome - 64-bit

baseurl=http://dl.google.com/linux/chrome/rpm/stable/x86_64

enabled=1

gpgcheck=1

gpgkey=https://dl-ssl.google.com/linux/linux_signing_key.pub

Install:

sudo yum install google-chrome-stable

1	sudo yum install google-chrome-stable

Run

google-chrome

1	google-chrome

CentOS 6: Install sudo and setup sudoers to use wheel group

1 Reply

Versions

CentOS 6.5

Install

Note	must be logged in as superuser

yum install sudo

1	yum install sudo

Configure

Add write access to /etc/sudoers before edit:

Shell

chmod u+w /etc/sudoers

1

chmod u+w /etc/sudoers
Edit /etc/sudoers and uncomment this line:

Default

## Allows people in group wheel to run all commands %wheel ALL=(ALL) ALL

1
2

## Allows people in group wheel to run all commands
%wheel ALL=(ALL) ALL
Remove write access otherwise sudo won’t run:

chmod u-w /etc/sudoers

1	chmod u-w /etc/sudoers

+ NOTE: user must have primary group as wheel to sudo. See CentOS 6: Change existing user group