Thursday 3rd of April 2025 10:56:54 AM
| workflow notes | dbconsole | dbnotes | Linux | ULN | vi cookbook |
logical volume manager (lvm) |
Unix
| Enabling and Starting NFS Server If you must use NFS, it can be activated using the following commands on Red Hat Linux:
chkconfig portmap on
chkconfig nfs on
service portmap start
service nfs start
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Determine the available RAM and swap space:
| # free |
Determine the RAM size:
| grep MemTotal /proc/meminfo |
Determine the amount of free disk space available in the /tmp directory
| # df -k /tmp or df -H /tmp |
Determine the size of the configured swap space:
| # grep SwapTotal /proc/meminfo |
Delete a bunch of files at once
| find . -name '*.log' \! -mtime -10 -exec rm {} \; |
Delete files by inodes. Use this if just by chance you accidently created a file with a name like * , which would delete everything in the directory if you tried to delete it with rm * instead of just deleting the file named "*" or whatever other dumb name you named the file you want to remove. Don't even ask, I've never created a file with a dumb name.
cd to the directory where the file resides
list the inode of the file you want to delete
ls -i or ls -ltrai 137003011 -rw-r--r-- 1 root root 3558 Aug 11 2009 install.log.syslog |
{ remove the file by the inode}
| find . -inum 137003011 -exec rm {} \; |
Rename the file to a normal name instead of removing it if you're uncomfortable deleting the funky named file You can then delete the renamed file. The new file name in this case is named "newname"
| % find . -inum 137003011 -exec mv {} newname \; |
find a file by something inside the file
find . type f -print | xargs grep -li whateveryouwanttosearchfor |
find a file by file type and name , then send the junk output to nowhere so it won't clog up your screen
| find / -type d -name "Updates" -print 2>/dev/null |
Kill multiple processes at once
| ps -ef|grep oratst |grep "LOCAL=NO" |awk '{ print $2 }' |xargs kill -9 |
If you want to remove the ^M characters, you can use dos2unix '/usr/bin/dos2unix' dos2unix a.txt b.txt or tr
tr -d '\r' < infile.txt > outfile.
|
Set Line #'s in a vi'd file
set number set nonumber
process Id variable
| $$ |
http://tldp.org/LDP/abs/html/internalvariables.html
http://www.debian-administration.org/articles/231
If you're root you can change the shell for a user by adding the username to the command line: |
| root@mystery:~# chsh skx |
You can also supply the shell name without being prompted for it interactively with the -s argument: |
| root@mystery:~# chsh -s /bin/zsh skx |
skx@mystery:~$ chsh -s /bin/bash Password: |
The correct way for a user to change his or her shell is via the chsh command. chsh stands for change shell, and does exactly what the name suggests. Invoke it with no arguments and you will be prompted for your password, then you will be prompted for your shell. The file /etc/shells is consulted, and your chosen shell must be included in there for your change to be accepted. If you enter the name of a binary which is not contained in /etc/shells you'll receive and error similar to this: |
skx@mystery:~$ chsh Password: Changing the login shell for skx Enter the new value, or press return for the default Login Shell [/bin/sh]: /bin/fff /bin/fff is an invalid shell. |
remove a package from linux
Tried to install rpm -ivh glibc-2.5-49.i686.rpm This errored with conflicts: part of the error: file /usr/share/i18n/charmaps/WINDOWS-31J.gz from install of glibc-common-2.5-49.x86_64 conflicts with file from package glibc-common-2.5-49.el5_5.7.x86_64 rpm -e glibc-common-2.5-49.el5_5.7.x86_64
Use this to remove the file with conflicts: rpm -e --nodeps glibc-common-2.5-49.el5_5.7.x86_64
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check if something's installed on Linux
rpm -aq |grep snmp
rpm -aq |grep telnet
install a package:
rpm -ivh
rpm -qa |grep up2date rpm -qa|grep yum rpm -qa --queryformat "|%{NAME}|%{VERSION}|%{RELEASE}|%{ARCH}|\n" | grep compat-db rpm -qa --queryformat "|%{NAME}|%{VERSION}|%{RELEASE}|%{ARCH}|\n" | grep <packageName> |
rpm -qa --queryformat "%{NAME}-%{VERSION}-%{RELEASE} (%{ARCH})\n" | grep libXp
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telnet 127.0.0.1 to escape: ^] telnet>quit nslookup earth.moon.com ping earth.moon.com traceroute earth.moon.com Send a test message. There is a "." after data
telnet earth.moon.com 25 helo earth.moon.com MAIL FROM: venus@earth.moon.com RCPT TO: zeus@earth.moon.com DATA . |
tail -f /var/log/maillog grep something /var/log/maillog |
how to mount NTFS harddrive on OEL Linux
Setup nfs mount to copy patches and disks from one server to another.
Add this directory to the NFS exports file /etc/exports
/oraclenfs *(rw,sync,all_squash,anonuid=500,anongid=500)
vi /etc/exports
<directory you want to share> <server you want to share it with><permissions you want to use> Don't add a space between the permissions and the server
| /u09 earth(rw) venus(rw) pluto(rw) /u10 earth(rw) venus(rw) pluto(rw) /data earth(rw) venus(rw) pluto(rw) |
| service nfs stop service nfs start |
From earth:
| Mount pluto:/u09 /data/mo |
From Venus
| mount earth:/u09 /data/lmu |
Check if the oraclefs directory is exported correctly by issuing the exportfs –v command.
exportfs -a
rpcinfo -p <servername>
Unable to umount an nfs file system. First check that you are not in the directory. This is the usual cause. Check if you have an open screen that is holding the directory. Use lsof if you have to. If you can't find anything holding it. (you have something , your probably in it.) You can force it to umount.
a lazy unmount:
umount -l /mnt/deadmount
(run as root):
# umount tmpfs
# mount -t tmpfs shmfs -o size=1300m /dev/shm
# df -k /dev/shm
Filesystem 1K-blocks Used Available Use% Mounted on
shmfs 1331200 0 1331200 0% /dev/shm
Did this instead: mount -t tmpfs -o size=2071016 tmpfs /dev/shm
http://blog.tanelpoder.com/2007/08/21/oracle-11g-internals-part-1-automatic-memory-management/
http://www.cyberciti.biz/tips/what-is-devshm-and-its-practical-usage.html
This didn't work for me...
For example, if you have 8GB RAM then remount /dev/shm as follows: # mount -o remount,size=8G /dev/shm To be frank, if you have more than 2GB RAM + multiple Virtual machines, this hack always improves performance.
# mount -t tmpfs -o size=5G,nr_inodes=5k,mode=700 tmpfs /disk2/tmpfs
The above will give you tmpfs instance on /disk2/tmpfs which can allocate 5GB RAM/SWAP in 5K inodes and it is only accessible by root.
How to umount when the device is busy
| # fuser -m /dev/sdc1 /dev/sdc1: 538 # ps auxw|grep 538 donncha 538 0.4 2.7 219212 56792 ? SLl Feb11 11:25 rhythmbox |
syslog-logwatch
/etc/cron.daily
0anacron cups makewhatis.cron prelink tmpwatch
0logwatch logrotate mlocate.cron rpm
0logwatch -> /usr/share/logwatch/scripts/logwatch.pl
adadmin logs:/u02/oracle/TEST/apps/apps_st/appl/admin/TEST/log/adamin_120109.log
start stop sendmailservice sendmail stop
/etc/init.d/sendmail stop
/etc/init.d/sendmail start
/etc/init.d/sendmail restart
Forward root email
/etc/aliases
add the Person who should get root email
Rebuild alias database (after aliasing root email to another user)
| # newaliases |
mailx monique9@gmail.com < <filename> (this mails the file in the body of the email)
To mail the file as an attachment use uuencodeIn Red Hat Linux, uuencode is part of the sharutils package. You'll have to add it. It's not installed by default.
rpm -ivh sharutils-4.6.1-2.x86_64.rpm (this is the package on OEL 5.3)
uuencode file file.name | mailx email@address uuencode input_file output_file | sendmail recipient(s)
uuencode input_file output_file | mail -s subject recipient(s)
uuencode input_file output_file | mailx -s subject recipient(s)
cat ${SUC_Template}.${DATE_TIME}.$$.tmp;uuencode ${ZIPFILE} "${SQL_NAME}.zp") | mailx -n -s "${SUBJECT}" ${BizEMailAddr} If change the mailx switch "-n" to "-m" it works. (cat $tmpbody; uuencode $filename $filename) | mail -s "${subject}" $location
uuencode -m input_file output_file | mail -s mail_subject recipient(s)
If you want to use ESC-K to see history:
ksh –o vi
send something to nowhere:
2>/dev/null
If you want to enter joe in the beginning of each line:
| :%s/^/joe/ |
If you want a space after joe ":%s/^/Joe /"
| :%s/^/joe / |
rpm -ivh <package name>
check if a package is installed:
rpm -q <package name>
Change username from tom to jerry
Type usermod command as follows:
# id tom
# usermod -l jerry tom
# id jerry
# id tom
Type usermod command as follows
# id tom
# usermod -u 10000 tom
# id tom
http://nixcraft.com/getting-started-tutorials/823-redhat-enterprise-linux-rhel-start-service-boot.html
ntsysv - simple TUI (text based interface) interface for configuring runlevels.
chkconfig - chkconfig provides a simple command-line tool for maintaining the /etc/rc[0-6].d directory hierarchy by relieving system administrators of the task of directly manipulating the numerous symbolic links in those directories
Turn on sshd service on boot
| chkconfig sshd on |
Turn on Apache / httpd service on boot
| chkconfig httpd on |
List if service is on or off on boot
| /sbin/chkconfig --list |
http://www.unix.com/answers-frequently-asked-questions/13527-cron-crontab.html
crontab -l > mycrontab vi mycrontab
|
Copy your crontab to a file edit the file and make your changes update crontab with your changes |
| 1. Crontab Restrictions You can execute crontab if your name appears in the file /usr/lib/cron/cron.allow. If that file does not exist, you can use crontab if your name does not appear in the file /usr/lib/cron/cron.deny. If only cron.deny exists and is empty, all users can use crontab. If neither file exists, only the root user can use crontab. The allow/deny files consist of one user name per line. |
2. Crontab Commands export EDITOR=vi ;to specify a editor to open crontab file. crontab -e Edit your crontab file, or create one if it doesn’t already exist. After editing the file, save it with cntrl-c |
* * * * * <command to be executed>
- - - - -
| | | | |
| | | | +----- day of week (0 - 6) (Sunday=0)
| | | +------- month (1 - 12)
| | +--------- day of month (1 - 31)
| +----------- hour (0 - 23)
+------------- min (0 - 59)
. Crontab Example 30 18 * * * rm /home/someuser/tmp/* |
Crontab Environment Users who desire to have their .profile executed must explicitly do so in the crontab entry or in a script called by the entry. |
6. Disable Email >/dev/null 2>&1 |
7. Generate log file 30 18 * * * rm /home/someuser/tmp/* > /home/someuser/cronlogs/clean_tmp_dir.log |
df's -i option instructs it to supply information about inodes on each filesystem rather than about available space. Specifically, it tells df to return for each mounted filesystem the total number of inodes, the number of free inodes, the number of used inodes and the percentage of inodes used. This option can be used together with the -h option as follows to make the output easier to read: |
|---|
| df -hi |
sudo dmidecode --type 17 or$ sudo dmidecode --type 17 | more
or dmidecode > code.txt - then check the text file for info
type 17: Handle 0x000D, DMI type 17, 27 bytes.
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Provide ANSI/VT100 terminal emulation, making it possible to run
multiple full-screen pseudo-terminals from one real terminal, and
letting you manipulate and save your screen input and output, copy
and paste between windows, etc.
http://www.oreillynet.com/linux/cmd/cmd.csp?path=s/screen
screen location: Screen is located on the Linux DVD under /Server
copy screen program to /data on earth
rpm ivh screen-4.0.3-1.el5.x86_64.rpm
Using Screen:
[root@earth Server]# screen
To open a new window, you just use “Ctrl-A” “c”.
To get back to top, use “Ctrl-A “n”
1. You kill the window with “Ctrl-A” “K” or “exit” will work on some systems. This will kill the current windows.
If you have other windows, you will drop into one of those. If this is the last window, then you will exit screen.
2. The second way to leave screen is to detach from a windows. This method leaves the process running and simply closes the window.
If you have really long processes, you need to close your SSH program, you can detach from the window using “Ctrl-A” “d”.
This will drop you into your shell. All screen windows are still there and you can re-attach to them later
3. Reattach to screen. Find the screens that are open:
| screen -ls |
To reattach to a screen with the -r flag and the session name.
| screen -r <session from ls> |
Using “Ctrl-A” “H”, creates a running log of the session
If Screen is attached elsewhere, holding an nsf mounted file system or some other random annoying thing. Your not able to attach to it., because it's attached to nothing.This is the long way if you don't know how to get rid of it, this will.
screen -ls -list out the screen screen -D <screen-listed> will detach the attached screen screen -r <screen-listed> will attach to the detatched screen exit - will exit out of the screen
-D
Detach session running elsewhere, logging out before detaching.With -r,
reattach to this terminal. With -R, reattach to this terminal or create
it if it doesn't already exist. With -RR, do whatever is necessary to
create a new session.How to connect to another user's console using screen:
http://ubuntuforums.org/showthread.php?t=299286
http://www.linuxquestions.org/questions/linux-general-1/problem-using-screen-cannot-open-your-terminal-dev-pts-0-please-check-338313/
Could not execute auto check for display colors using command /usr/X11R6/bin/xdpyinfo. Check if the DISPLAY variable is set." Once the location is determined, create a link to the correct location:ln -s <actual path to file>/xdpyinfo <expected path to file>/xdpyinfoi.eln -s /usr/bin/xdpyinfo /usr/X11R6/bin/xdpyinfo
Logwatch http://www.stellarcore.net/logwatch/tabs/docs/HOWTO-Customize-LogWatch.html
usr/share/logwatch
Cowsay http://www.nog.net/~tony/warez/cowsay.shtml
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