Basic
File Navigation
·
The "pwd" command displays the current
directory.
root> pwd
/u01/app/oracle/product/9.2.0.1.0
·
The "ls" command lists all files and
directories in the specified directory. If no location is defined it acts on
the current directory.
root> ls
root> ls /u01
root> ls -al
The "-a" flag lists
hidden "." files. The "-l" flag lists file details.
·
The "cd" command is used to change
directories.
root> cd /u01/app/oracle
·
The "touch" command is used to create
a new empty file with the default permissions.
root> touch my.log
·
The "rm" command is used to delete
files and directories.
root> rm my.log
root> rm -R /archive
The "-R" flag tells the
command to recurse through subdirectories.
·
The "mv" command is used to move or rename
files and directories.
root> mv [from] [to]
root> mv my.log my1.log
root> mv * /archive
root> mv /archive/* .
The "." represents the
current directory.
·
The "cp" command is used to copy files
and directories.
root> cp [from] [to]
root> cp my.log my1.log
root> cp * /archive
root> cp /archive/* .
·
The "mkdir" command is used to create
new directories.
root> mkdir archive
·
The "rmdir" command is used to delete
directories.
root> rmdir archive
·
The "find" command can be used to find
the location of specific files.
root> find / -name dbmspool.sql
root> find / -print | grep -i dbmspool.sql
The "/" flag represents
the staring directory for the search. Wildcards such as "dbms*" can
be used for the filename.
·
The "which" command can be used to
find the location of an executable you are using.
oracle> which sqlplus
The "which" command
searches your PATH setting for occurrences of the specified executable.
File Permissions
·
The "umask" command can be used to
read or set default file permissions for the current user.
root> umask 022
The umask value is subtracted from
the default permissions (666) to give the final permission.
666 : Default permission
022 : - umask value
644 : final permission
·
The "chmod" command is used to alter
file permissions after the file has been created.
root> chmod 777 *.log
Owner Group World
Permission
========= ========= =========
======================
7 (u+rwx) 7 (g+rwx) 7 (o+rwx)
read + write + execute
6 (u+wx) 6 (g+wx) 6 (o+wx)
write + execute
5 (u+Rx) 5 (g+Rx) 5 (o+Rx)
read + execute
4 (u+r) 4 (g+r) 4 (o+r)
read only
2 (u+w) 2 (g+w) 2 (o+w)
write only
1 (u+x) 1 (g+x) 1 (o+x)
execute only
·
Character eqivalents can be used in the chmod
command.
root> chmod o+rwx *.log
root> chmod g+r *.log
root> chmod -Rx *.log
·
The "chown" command is used to reset
the ownership of files after creation.
root> chown -R oinstall.dba *
The "-R" flag causes the
command ro recurse through any subdirectories.
OS Users Management
·
The "useradd" command is used to add
OS users.
root> useradd -G oinstall -g dba -d
/usr/users/my_user -m -s /bin/ksh my_user
The "-G" flag specifies the primary group.
The "-g" flag specifies the secondary group.
The "-d" flag specifies the default directory.
The "-m" flag creates the default directory.
The "-s" flag specifies the default shell.
·
The "usermod" command is used to
modify the user settings after a user has been created.
root> usermod -s /bin/csh my_user
·
The "userdel" command is used to
delete existing users.
root> userdel -r my_user
The "-r" flag removes the
default directory.
·
The "passwd" command is used to set,
or reset, the users login password.
root> passwd my_user
·
The "who" command can be used to list
all users who have OS connections.
root> who
root> who | head -5
root> who | tail -5
root> who | grep -i ora
root> who | wc -l
The "head -5" command restricts the output to the first 5
lines of the who command.
The "tail -5" command restricts the output to the last 5 lines
of the who command.
The "grep -i ora" command restricts the output to lines
containing "ora".
The "wc -l" command returns the number of lines from
"who", and hence the number of connected users.
Process Management
·
The "ps" command lists current process
information.
root> ps
root> ps -ef | grep -i ora
·
Specific processes can be killed by specifying
the process id in the kill command.
root> kill -9 12345
uname and hostname
·
The "uname" and "hostname"
commands can be used to get information about the host.
root> uname -a
OSF1 oradb01.lynx.co.uk V5.1 2650 alpha
root> uname -a | awk '{ print $2 }'
oradb01.lynx.co.uk
root> hostname
oradb01.lynx.co.uk
·
Error Lines in Files
You can return the error lines in
a file using.
root> cat alert_LIN1.log | grep -i ORA-
The "grep -i ORA-"
command limits the output to lines containing "ORA-". The
"-i" flag makes the comparison case insensitive. A count of the error
lines can be returned using the "wc" command. This normally give a word
count, but the "-l" flag alteres it to give a line count.
root> cat alert_LIN1.log | grep -i ORA- | wc -l
Alias
·
An alias is a named shortcut for a longer
command using the following format.
alias name='command'
For example, if you require sudo
access for a specific command, you might want to include this as an alias so
you don't have to remember to type it.
alias myscript='sudo -u oracle
/path/to/myscript'
Remove DOS CR/LFs (^M)
·
Remove DOS style CR/LF characters (^M) from UNIX
files using.
sed -e 's/^M$//' filename > tempfile
The newly created tempfile should
have the ^M character removed.
Where available, it is probably
better to use the dos2unix and unix2dos commands.
Compress Files
In order to save space on the
filesystem you may wish to compress files such as archived redo logs. This can
be using either the gzip or the compress commands. The gzip command results in
a compressed copy of the original file with a ".gz" extension. The
gunzip command reverses this process.
gzip myfile
gunzip myfile.gz
The compress command results in a
compressed copy of the original file with a ".Z" extension. The
uncompress command reverses this process.
compress myfile
uncompress myfile
General Performance
vmstat
Reports virtual
memory statistics.
# vmstat 5 3
procs -----------memory---------- ---swap-- -----io---- --system--
-----cpu------
r
b swpd free
buff cache si
so bi bo
in cs us sy id wa st
0
0 0 1060608 24372 739080 0
0 1334 63 1018 1571 14 11 66 10 0
0
0 0 995244 24392 799656 0
0 6302 160 1221 1962 10 10 62 18 0
0
0 0 992376 24400 799784 0
0 1 28
992 1886 3 2 95
0 0
#
free
Reports the current memory usage.
The "-/+ buffers/cache:" line represents the true used and free
memory, ignoring the Linux file system cache.
# free
total used free
shared buffers cached
Mem: 8178884 4669760
3509124 0 324056
1717756
-/+ buffers/cache: 2627948 5550936
Swap: 10289148 0
10289148
#
iostat
Reports I/O statistics.
# iostat
Linux 3.2.10-3.fc16.x86_64 (maggie.localdomain) 03/19/2012 _x86_64_(4
CPU)
avg-cpu: %user %nice %system %iowait %steal
%idle
2.02 0.23
0.51 0.78 0.00
96.46
Device: tps kB_read/s
kB_wrtn/s kB_read kB_wrtn
sda 9.23 100.55 62.99
1796672 1125538
dm-0 13.60 100.31 62.99
1792386 1125524
dm-1 0.02 0.08 0.00 1432 0
CPU Usage
sar
On Linux systems sar (System
Activity Reporter) is probably one of the simplest and most versatile tools for
reporting system utilization including CPU, memory, disk and network activity.
It automatically collects system activity statistics when installed using the
following command.
# yum install sysstat
The sar command syntax takes the
following form.
# sar [options] [interval [count]]
top
Displays top tasks.
CRON
There are two methods of editing
the crontab file. First you can use the "crontab -l > filename"
option to list the contents and pipe this to a file. Once you've editied the
file you can then apply it using the "crontab filename".
Login as root
crontab -l > newcron
Edit newcron file.
crontab newcron
Alternatively you can use the
"crontab -e" option to edit the crontab file directly.
The entries have the following
elements.
field allowed values
----- --------------
minute 0-59
hour 0-23
day of month 1-31
month 1-12
day of week 0-7 (both 0 and 7
are Sunday)
user Valid OS user
command Valid command or
script.
The first 5 fields can be specified
using the following rules.
* - All available values or
"first-last".
3-4 - A single range
representing each possible from the start to the end of the range inclusive.
1,2,5,6 - A specific list of values.
1-3,5-8 - A specific list of ranges.
0-23/2 - Every other value in the
specified range.
The following entry runs a cleanup
script a 01:00 each Sunday. Any output or errors from the script are piped to
/dev/null to prevent a buildup of mails to root.
0 1 * * 0
/u01/app/oracle/dba/weekly_cleanup > /dev/null 2>&1
