fstab error, can't boot, can't edit fstab

Centos /Fedora OS

Fr. terminal

#  "mount -o remount,rw /"

then save and reboot

Getting to know your Hardware

Getting to know your HW of your linux box.

From terminal: Type: hdparm -I /dev/sda | grep Serial

source: http://linuxconfig.org/getting-know-a-hardware-on-your-linux-box

Creating/renaming network device i.e eth1 ; eht2

Creating/renaming stable names for network interfaces

to edit or rearrange device name on centos

vi /etc/udev/rules.d/70-persistent-net.rules

Installation and configuration of MRTG - Centos 6.3

Procedure:

From the terminal:
#: yum install snmp

Check if snmp is installed
# rpm -qa | grep snmp

Start the service fr. the terminal
# service snmpd start
#chkconfig snmpd on ( to start the service after reboot)

Configuration.

# vi /etc/snmp/snmpd.conf

enter the ff:
rocommunity     craz33guy
disk               /

where cras33guy = userrname

From terminal
# cfgmaker --global 'workdir: /var/www/mrtg/mymrtg' --output /etc/mrtg/mrtg.cfg craz33guy@192.168.60.xxx

# env LANG=C LC_ALL=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg --lock-file /var/lock/mrtg/mrtg.l --confcache-file /var/lib/mrtg/mrtg.ok
# indexmaker  --output=/var/www/mrtg/index.html /etc/mrtg/mrtg.cfg

then open /etc/#vi /etc/mrtg - edit the necessary changes
I.E.  mrtgTitle[192.168.60.191_192.168.60.191]: Traffic Analysis for 3 -- row-based|\


TWO CONNECT OTHER SERVER/UNIT

Fr. /etc/mrtg/dotxxx
Edit the ff:
# cd /etc/mrtg### Interface 3 >> Descr: 'eth0' | Name: 'eth0' | Ip: '192.168.60.191' | Eth: '00-13-46-3c-80-77' ###
Target[192.168.60.xxx_192.168.60.xxx]: /192.168.60.xxx:craz33guy@192.168.60.xxx:
SetEnv[192.168.60.xxx_192.168.60.xxx]: MRTG_INT_IP="192.168.60.xxx" MRTG_INT_DESCR="eth0"
MaxBytes[192.168.60.xxx_192.168.60.xxx]: 12500000
#mkdir dotxxx i.e dot191
Title[192.168.60.191_192.168.60.191]: Traffic Analysis for 3 -- row-based|\
PageTop[192.168.60.191_192.168.60.191]: <h1>192.168.60.191 -- row-based </h1>
                <div id="sysdetails">
                        <table> <tr> <td>System:</td> <td>row-based in Unknown</td>
                                </tr> <tr> <td>Maintainer:</td><td>root@localhost</td>
                                </tr> <tr><td>Description:</td> <td>eth0  </td>
                                </tr> <tr><td>ifType:</td><td>ethernetCsmacd (6)</td>
                                </tr>
                                <tr><td>ifName:</td> <td>eth0</td>
                                </tr>
                                <tr> <td>Max Speed:</td><td>12.5 MBytes/s</td>
                                </tr>
                                <tr> <td>Ip:</td> <td>192.168.60.191 ()</td>
                                </tr>
                        </table>
                </div>
then type

# env LANG=C /usr/bin/mrtg /etc/mrtg/dot191/dot191.cfg --lock-file /var/lock/mrtg/dot191._l --confcache-file /var/lib/mrtg/dot191.ok

# indexmaker --output=/var/www/mrtg/index.html /etc/mrtg/mrtg.cfg /etc/mrtg/dot191/dot191.cfg

To VIEW MRTG
Fr. browser type
192.168.60.xxx/mrtg

Configuring NFS Server

[1]	It's the Configuration on the system you want to build NFS server.

[root@dlp ~]# yum -y install nfs-utils [root@dlp ~]# vi /etc/idmapd.conf # line 5: uncomment and change to your domain name Domain = server.world [root@dlp ~]# vi /etc/exports # write like below *note /home 10.0.0.0/24(rw,sync,no_root_squash,no_all_squash) # *note /home ⇒ shared directory 10.0.0.0/24 ⇒ range of networks NFS permits accesses rw ⇒ writable sync ⇒ synchronize no_root_squash ⇒ enable root privilege no_all_squash ⇒ enable users' authority [root@dlp ~]# /etc/rc.d/init.d/rpcbind start Starting rpcbind: [  OK  ] [root@dlp ~]# /etc/rc.d/init.d/nfslock start Starting NFS statd: [  OK  ] [root@dlp ~]# /etc/rc.d/init.d/nfs start RPC: Registered udp transport module. RPC: Registered tcp transport module. RPC: Registered tcp NFSv4.1 backchannel transport module. Installing knfsd (copyright (C) 1996 okir@monad.swb.de). Starting NFS services: [  OK  ] Starting NFS daemon: NFSD: Using /var/lib/nfs/v4recovery as the NFSv4 state recovery directory NFSD: starting 90-second grace period [ OK ] Starting NFS mountd: [ OK ] [  OK  ] Starting RPC idmapd: [ OK ] [  OK  ] [root@dlp ~]# chkconfig  rpcbind on [root@dlp ~]# chkconfig nfslock on [root@dlp ~]# chkconfig nfs on Configuration on NFS clients [root@www ~]# yum -y install nfs-utils # install [root@www ~]# vi /etc/idmapd.conf # line 5: uncomment and change to your domain name Domain = server.world [root@www ~]# /etc/rc.d/init.d/rpcbind start Starting rpcbind: [  OK  ] [root@www ~]# /etc/rc.d/init.d/rpcidmapd start Starting RPC idmapd: RPC: Registered udp transport module. RPC: Registered tcp transport module. RPC: Registered tcp NFSv4.1 backchannel transport module. [ OK ] [root@www ~]# /etc/rc.d/init.d/nfslock start Starting NFS statd: [  OK  ] [root@www ~]# /etc/rc.d/init.d/netfs start Mounting other filesystems: [  OK  ] [root@www ~]# chkconfig rpcbind on [root@www ~]# chkconfig rpcidmapd on [root@www ~]# chkconfig nfslock on [root@www ~]# chkconfig netfs on [root@www ~]# mount -t nfs dlp.server.world:/home /home [root@www ~]# df -h Mounted on 192.168.xx.x:/var/spool/asterisk/incoming      272G   36G  222G  14% /var/www/html/recordings/incoming # home directory on NFS is mounted [root@www ~]# vi /etc/fstab # add at the lat line:  server mounts to the one on NFS /192.168.xx.x:/var/spool/asterisk/incoming  /var/www/html/recordings/incomin                                  g             nfs  hard,intr   0 0

Finding a File containing a particular text string in Linux server

You need to use grep command. grep searches the given input FILEs for lines containing a match or a text string.

grep command form (syntax)

grep “text string to search” directory-path or ip addtress

Examples

For example search for a string called redeem reward in all text files located in /home/guest/*.txt directory, use
$ grep "192.168.xx.xx" /home/guest/*.txt

Task: Search all subdirectories recursively

You can search for a text string all files under each directory, recursively with -roption:
$ grep -r "192.168.xx.xx" /home/guest

Task: Only print filenames

By default, grep command prints the matching lines You can pass -H option to print the filename for each match.
$ grep -H -r “192.168.xx.xx” /home/guest
Output:

...
filename.txt: 192.168.xx.xx
...

To just print the filename use cut command as follows:
$ grep -H vivek /etc/* -R | cut -d: -f1



Output: