Maybe you are looking for a particular phrase in log files or maybe you are a programmer and need to find some string that is inside many different code files?

Here is how you can find and replace a string in several text files.

For this example, the Oracle DBA wants to replace  strings NSR* in all rman scripts:

#!/usr/bin/ksh

for base in /oracle/scripts/rman/rcv/*.rcv
do
TMP=$(mktemp test.XXXXXX)
sed 's/NSR_SERVER=networker-hme0, NSR_DATA_VOLUME_POOL=BU UNT FULL/NSR_SERVER=freppax-laaf02h, NSR_DATA_VOLUME_POOL=FullHP/g' $base > "$TMP" && mv "$TMP" $base
done

export PS1="\$ORACLE_SID $LOGNAME@$(hostname):\${PWD}> "
stty erase ^H
export HISTSIZE=100
export EDITOR=vi
set -o vi
alias ll="ls -altr"
umask 022

Sometimes the Oracle DBA has to I delete a Unix user account under Linux operating systems including the home directory.

How do I expire, delete or remove a user’s access from my server?

Deleting user account in Linux is an administrative task to remove user login credentials from system configuration files such as /etc/passwd, /etc/shadow and files which are owned by that particular user from the Unix server.

These command must be run as root user on Linux.

# Just Lock the password
usermod -L myusername

# Just Expire the account
chage -E0 myusername

# Delete the account. userdel is a low level utility for removing users. On Debian, administrators should usually use deluser instead.

# Be careful, User deletion is irreversible!
userdel myusername

-- Use these 2 options to delete that user's home directory and the spool of mails
-r : Remove Unix user account including home directory and mail spool
-f : Delete Linuxuser account with force removal of files

The userdel command modifies the following system account files:
/etc/group, /etc/login.defs, /etc/shadow, /etc/subgid and /etc/subuid.

How to clean associated objects?

If you want to clean other objects like cron jobs, files, print jobs; you will have to do it manually like that.

How to clean cron table
crontab -r -u myusername

How to clean print jobs
lprm myusername

How to change the owner of files owned by myusername
find / -user myusername -exec chown newUserName:newGroupName {} \;

Author: Vincent Fenoll, Oracle DBA in Montreal

A snapshot is a read-only copy of a file system or volume. Snapshots can be created almost instantly, and they initially consume no additional disk space within the pool. It’s important for the Oracle DBA in Montreal to have a list of these commands.

How can I create a new ZFS snapshot?

$sudo zfs snapshot rpool/DBORA/u01@u01snapshop

How can I list all ZFS files system and snapshots (in Bold)?

$ zfs list -r -t all

Or

$ zfs list -o space -r rpool

How can I know the creation date of the ZFS snapshots?

$ zfs list -r -t snapshot -o name,creation

How can I delete a ZFS snapshop?

$ sudo zfs destroy rpool/DBORA/u01@now

How can I use my ZFS snapshop to restore a single file?

I want to restore the file /u01/test.sh

$cd /u01
$cd .zfs/snapshot/u01snapshop/
$cp test.sh /u01/

or to restore a copie without replace current one :

$cp test.sh /u01/test2.sh

You can use a snapshot like any other (read-only) FS to move files or folder to another place.

How can I use my ZFS snapshop to restore a File system?

This command will discard all changes made to the file system since the snapshot was created:

$sudo zfs rollback rpool/DBORA/u01@u01snapshop
cannot rollback to ‘rpool/DBORA/u01@u01snapshop’: more recent snapshots exist
use ‘-r’ to force deletion of the following snapshots:
rpool/DBORA/u01@u01snapshop2
rpool/DBORA/u01@u01snapshop3

$sudo zfs rollback -r rpool/DBORA/u01@u01snapshop


More informations in the Oracle documentation.


Vincent Fenoll DBA Oracle Montreal