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du -hx --max-depth=1
xauth merge ~/.Xauthority
2>&1

Current kernel boot parameters

cat /proc/cmline

Find a running process The first character in brackets is the key, let's you avoid the grep -v grep, etc.

ps aux (or -elf) | grep '[a]ny_.*_process'

File/directory with spaces or special characters:

cd dir\ with \ spaces
cd ./-dont_do_this

for i in item1 item2 item3 ; do something ; done
for i in `cmd` ; do something ; done
for i in {1..9} ; do something ; done
for i in `seq start increment end` ; do something ; done
for ((init, condition, increment)); do something ; done

Ext3

• dumpe2fs {mount point}
• In output look for “Backup superblock”
• e2fsck -b {backup superblock} {mount point}

Look for state not equal “clean”

dumpe2fs {path_to_block_device} | grep state

set -o vi sets editor to vi set -vx sets command tracing (+vx to turn off)

select i in list ; do something ; done

Escape out of telnet or Xen console = Ctrl+]

awk -F{delim} '/search_pattern/ { print $1 }'

Background running job

• xeyes
• ^Z
• bg

vi from less/more = v

• No boot - grub prompt
  • rescue mode
  • grub-install boot_device (ie /dev/sda)
• No boot - corrupt grub
  • root(hd0,0) = hd#,part#
  • setup(hd0)
  • exit

crontab: minute hour dayofmonth month dayofweek command

Calc (simple):

echo $[ a + b ]

Calc (better):

echo "a / b" | bc

Make big file:

dd if=/dev/zero of=bigfile bs=1k(1M) count=N

SSH tunnelling on gumstix:

ssh -L 443:192.168.1.100:22 -g localhost

remote:

ssh mtonneson.homelinux.org -p 443

HOST: RHEL AP 5.4 with KVM and libvirt installed.

• Have to do a yum erase libvirt for RHEV-M install to work.
• Failed to create RHEVM bridge - needed to reinstall.
• No message or warning regarding auto-rebooting RHEL HOST - NOT GOOD!
• Reinstall from “click here” does not work - endless loop - must activate-
  • must put into maintenance - then can't connect. Only way is to deleteand re-add.
• FC - powerpath works but can't filter out emcpower in lvm.conf or thedisk creation will fail, in RHEV-M

RHCE Study Topics

 Local users & groups
 Cron/crontab
 tcpwrappers
 SELinux
 NFS server
 vsftpd
 sendmail/postfix
 apache
 dhcpd

1. Kernel loads
2. Writes to /var/log/messages
3. Starts init daemon
4. Reads /etc/inittab
5. Runs /etc/rc.d/rc.sysinit
6. Runs /etc/rc.d/rc.local
7. rc.sysinit logs to /var/log/dmesg
8. Additional logging to /var/log/boot.log

 man -a <keyword> = shows all pages matching keyword

program root - usually /etc/httpd/conf or /usr/local/apache web root - usually /home/httpd or /var/www/htdocs config file - httpd.conf

apachectl - control script

• start/stop/restart
• graceful - continues current child procs before restart
• configtest - tests syntax of httpd.conf
• status/fullstatus

inetd

 /etc/services        - lists network services and ports
 /etc/inetd.conf        - config file

xinetd

 /etc/xinetd.conf        - config file
 /etc/xinetd.d/        - service specific parameter files

Debian package mgmt

 dpkg
    --install                - install package
    --remove                - remove package
    --print-avail        - general info about package
    --list                - list installed packages
    --listfiles        - list files installed by package
    --status                - full package details
    --search                - which package owns/installed file

 /var/lib/dpkg/available        - available packages
 /var/lib/dpkg/status                - package status

 dselect         - menu driven version of dkpg
 apt-get         - cmdline package installer
 alien        - package converter

RHEL3 local login w/o LDAP:

 Try adding the following to nss_initgroups_ignoreusers line 
 to the file /etc/ldap.conf:

Just assume that there are no supplemental groups for these named users nss_initgroups_ignoreusers root,ldap,named,avahi,haldaemon,dbus,radvd,tomcat,radiusd,news,mailman,ntp,smmsp,xfs

RH Virtualization

 aws.amazon.com
 ec2
 SPEC Virt
 overt.et.redhat.com

passwd: ldapsearch -x -v -h directory -b “o=domain.com” “uid=UID”

VM install = cdrom://hdc:/mnt/source

vmware-cmd -l | xargs -ipath -t -e vmware-cmd path getpid

Installing VMware Tools in a Linux Guest

Choose Settings > VMware Tools Install, then click Install. This step connects the virtual machine's CD-ROM drive to an ISO image file on the ESX Server machine.

In your Linux guest, become root, mount the VMware Tools virtual CD-ROM, copy the installer file from the virtual CD-ROM to /tmp, then unmount the CD-ROM.

mount -t iso9660 /dev/cdrom /mnt
cp /mnt/vmware-linux-tools.tar.gz /tmp
umount /dev/cdrom

Untar the VMware Tools tar file in /tmp and install it.

cd /tmp
tar zxf vmware-linux-tools.tar.gz
cd vmware-tools-distrib
./vmware-install.pl

Note: When installing VMware Tools in some versions of Linux, the installer will need to recompile VMware Tools. For this to work, you need to have a C compiler installed in the guest. In some cases you may get compiler warning messages during the VMware Tools installation. However, the control panel and drivers still work correctly.

Follow the remaining steps. Choose directories for the various files. Choose a display size for the virtual machine. Enter the number for the choice and press Enter. If you wish, start X and your graphical environment and launch the VMware Tools background application.

vmware-toolbox &

Note: If you created this virtual machine using the vmxnet driver, you now need to run netconfig or another network configuration utility in the virtual machine to set up the virtual network adapter.

During operation, the service logs events from the infrastructures on tty1 through tty10 (if available), as well as /var/log/messages. If this produces too much text on the screen, adding the option “-V0x0” to the hprsm startup script will silence the text.

Server rename

 /etc/hosts
 /etc/sysconfig/network
 /usr/openv/netbackup/bp.conf
 Restart nscd service

smbclient //windows/share -W activedirectory.domain.com -U username
mount -t smbfs -o username=user,workgroup=activedirectory.domain.com 
//server/share /mnt/smb

Upgrade VM RHEL4.0 → RHEL4.2

1. cp {BusLogic}.ko /root/
2. shutdown
3. Connect floppy and CD
4. LSILogic → {BusLogic}
5. Update to RHEL4.2 (linux dd text)
6. boot linux rescue
7. cp /etc/modprobe.conf.anacbak /etc/modprobe.conf
8. add 'alias scsi_hostadapter {BusLogic}' to modprobe
9. cat /etc/issue.rpmsave > /etc/issue
10. cp /root/BusLogic.ko /lib/modules/2.6.9-22.EL/kernel/drivers/scsi/
11. mkinitrd -v -f /boot/initrd-2.6.9-22.EL-buslogic.img 2.6.9-22.EL
12. edit grub.conf - add new initrd
13. reboot
14. /usr/bin/vmware-config-tools.pl