Oracle Support

Key System Configuration Files

• /etc/exports – Contains file systems which may be exported to NFS clients
• /etc/fstab – Contains file systems mounted automatically at boot. Similar to /etc/vfstab for Solaris
• /etc/grub.conf – Configuration file for grub boot loader
• /etc/init.d – Control scripts that run at startup and shutdown to start/stop system processes
• /etc/inittab – Describes processes that startup at different runlevels as defined in /etc/init.d
• /etc/lilo.conf – Configuration file for lilo boot loader
• /etc/ocfs.conf – Oracle cluster file system config file
• /etc/profile.d – Default environment scripts to initialize system wide environment variables during login
• /etc/raidtab – Configuration file for raid (md) devices
• /etc/security/limits.conf – Configuration file containing resource limits for a user
• /etc/sysconfig – Directory where many files that control system configuration are stored
• /etc/sysctl.conf – Contains installation specific tunable kernel parameters (shmmax, shmmni, etc.)
• /etc/updatedb.conf – Config file for slocate (updatedb) used to index file locations for fast searching
• /etc/xinetd.d – Contains configuration files for different inet services (rsh, ftp, imap, etc.)
• /etc/X11/XF86Config – X-windows configuration file
• /proc/cpuinfo – Contains cpu count and processor info
• /proc/meminfo – Contains memory size, free memory, swap size, etc
• /proc/mdstat – Contains raid meta device information
• /proc/swaps – Contains swap information
• /proc/sys/kernel/sem – Contains current kernel semaphore settings
• /proc/sys/kernel/shmmax – Contains current kernel max shared memory settings
• /proc/sys/kernel/shmmni – Contains current kernel shared memory identifier settings

System Information Commands

• chkconfig – Updates and queries runlevel information for system services configured in /etc/rc[0-6].d directories
• chroot “directory” – Invoke a new shell, using “directory” as new root directory
• dmesg – List messages displayed during boot process
• kudzu – Detect and configure new/changed hardware
• ldd “program” – Display shared library dependencies
• lsmod – Display info about all loaded kernel modules
• lsof – List open files
• pstree -ca – Display process info in tree format
• shutdown -t 60 -r time “mesg” – Initiate shutdown at “time”, wait 60 secs between warning and kill signals, send “mesg” to users, then reboot after shutdown
• startx – Switch from text mode to X-windows mode
• strace – Trace system calls and signals, useful for debugging and troubleshooting failed system calls

File System Management Commands

• fdformat /dev/fd0H1440 – Format high density floppy
• fdisk -l – List partition table for all disk devices
• fdisk /dev/hda – Manage partition table for /dev/hda
• hdparm -i /dev/hda – Display hard drive performance parameters; useful for tuning exercises
• hdparm -i -d1 -m16 -c3 -k1 /dev/hda – Set hard drive performance parameters (dma=1, multi-sectors=16, 32 bit i/o mode=3, keep settings=1) for /dev/hda
• mkbootdisk “kernel” – Make floppy boot disk (default device /dev/fd0) for “kernel”, which must be listed in output of “ls /lib/modules” command
• mk2efs -m 1 -j /dev/hdb5 – Make ext3 file system on partition 5 for device /dev/hdb, leave 1% free for root
• mkfs.ocfs /dev/hdb1 – Create OCFS file system
• mkswap /dev/hdb1 – Create swap space on /dev/hdb1
• mount -t iso9660 /dev/cdrom /mnt/cdrom – Mount a cdrom device on /mnt/cdrom
• mount -t vfat /dev/hda9 /mnt – Mount a Windows fat32 file system for device /dev/hda9 on /mnt
• mcopy “file1” “file2” – Copy MSDOS file to/from floppy (ex: mcopy /etc/hosts a:myhost.txt)
• sftp host – Start secure ftp session as remote “user” on “host”
• swapon /dev/hdb1 – Enable swapping on /dev/hdb1
• tune2fs -L /vol2 -j /dev/hda2 – Convert ext2 file system to ext3 on device /dev/hda2, set label to /vol2
• tune2fs -l /dev/hda1 – List file system super block information for partition /dev/hda1
• umount “filesystem” – Unmount file system

Network Information Commands

• dig “domain” – Perform DNS lookup for “domain” and display results from the name server
• ifconfig -a – Display all network interfaces configured
• lsof -i – Show processes using ports
• netstat -a – Display network statistics for all ports
• netstat -rn – Display network statistics for routing tables
• tcpdump – Dump traffic on network

Package Management Commands

• rpm -qa – Query all installed packages
• rpm -qil "package" – Query package name “package”, show all info, list package files
• rpm -ivh “package” – Install new package name “package”, verbosely, show progress hash marks
• rpm -uvh “package” – Upgrade new package name “package”, verbosely, show progress hash marks
• rpm -e “package” – Erase (remove) package
• up2date – Automated install and upgrade of all or selected packages to current versions (Red Hat)

User Management Files & Commands

• $HOME/.bash_profile – executed automatically at login $HOME/.bash_logout – executed automatically at logout
• chage – Change password and expiration information
• chage -d0 – Force user to change password next login
• chsh – Change login shell
• groupadd “group” – Add new group “group”
• passwd “user” – Set password for “user” (run as root)
• passwd – Set new password for current user
• pwconv – Create /etc/shadow from /etc/passwd
• ssh host – Logon to remote host as “user” with secure shell protocol
• ulimit -a – Display all resource limits for current user
• useradd -d home_dir -g primary_group -G
• secondary_group “username” – Add user “username”

Backup, Restore, and File Transfer Commads

• curl “url” – Transfer data from or to a server using http, https, ftp, etc protocols
• scp “host:file1 file2” – Copy file1 on remote host to local file2 using secure copy
• tar -xzvf “tarfile” – Extract files from compressed tar file “tarfile”. Similar to “gzip -dc | tar xvf -”
• tar -czvf “tarfile” – Create compressed tar file of files in current directory. Similar to “tar cvf - * | gzip -dc”
• unzip “zipfile” “pattern” – Extract from compressed “zipfile” files matching “pattern” into current directory. If “pattern” is omitted, extract all files
• zip -r “zipfile” “pattern” – Create compressed “zipfile” from files/directories matching “pattern” recursively

Miscellaneous Commands

• dircolors – Setup terminal for color ls command
• import – Screen capture tool included with ImageMagick
• import -frame “filename.jpg” – Capture screen with a mouse click on the window, including window frame
• info – Documentation on Linux commands and programs
• opcontrol – Hardware performance profiler

Setting Kernel Parameters

Unlike legacy UNIX, with Linux you can quickly set kernel params without rebooting; to set values for Oracle, perform the following: (order is semmsl semmns semopm semmni for semaphores, max shared memory, shared memory identifiers, max file descriptors, min_port max_port for port range)

• echo 250 32000 100 128 > /proc/sys/kernel/sem
• echo 2147483648 > /proc/sys/kernel/shmmax
• echo 100 > /proc/sys/kernel/shmmni
• echo 65536 >/proc/sys/fs/file-max
• echo 1024 65000  > /proc/sys/net/ipv4/ip_local_port_range

To make the settings persistent after rebooting, add them /etc/sysctl.conf:

• kernel.sem = 250 32000 100 128
• kernel.shmmax = 2147483648
• kernel.shmmni = 100
• kernel.shmall = 2097152
• fs.file-max = 65536
• net.ipv4.ip_local_port_range = 1024 65000 

Setting Process limits

• ulimit -n 65536
• ulimit -u 16384

To make the settings persistent after rebooting, add them to /etc/security/limits.conf:

• oracle soft nofile 65536
• oracle hard nofile 65536
• oracle soft nproc 16384
• oracle hard nproc 16384

Adding Interim Swap Space

Determine file system with free space to hold extra swap space. Then, perform the following (adds 1GB swap):

• dd if=/dev/zero of=tempswap bs=1k count=1048576
• chmod 600 tempswap
• mkswap tempswap
• swapon tempswap
• Remove the interim swap when it’s no longer needed:
• swapoff tempswap; rm tempswap

Adding Interim /tmp Space

Determine an ext2/ext3 file system with enough space to hold required tmp space. Then, perform the following:

• mkdir /interim_filesystem/tmp
• chgrp root /interim_filesystem/tmp
• chmod 1777 /interim_filesystem/tmp
• Before running the program that needs extra /tmp (like runInstaller for Oracle), perform the following:
• TEMP=/interim_filesystem/tmp; export TEMP
• TMPDIR=/interim_filesystem/tmp; export TMPDIR

Configuring an OCFS File System

Download rpm’s from http://oss.oracle.com/projects/ocfs and install:

• rpm -ivh ocfs*.rpm
• Next, create /etc/ocfs.conf:
• cat <<eof>>/etc/ocfs.conf
• node_name = localhost.localdomain
• ip_address = 10.0.0.1
• ip_port = 7000
• comm_voting = 1
• eof

Create the unique identification key and load OCFS the first time (boot process runs load_ocfs automatically):

• ocfs_uid_gen -c
• load_ocfs

Make an OCFS file system (choose any empty partition):

• mkfs.ocfs -b 128 -g dba -u oracle -L "/ocfstest2" –m /ocfstest2 /dev/hdg5
• Mount the new OCFS file system on /ofcstest:
• mount -t ocfs /dev/hdg5 /ocfstest