Working with the Unix OS

Unix Administration
/tmp, /var/tmp, /usr/tmp # scratch pads fill up fast
/usr/spool/console, /usr/adm/messages, ...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
UBUNTU: /usr/spool/ does not exist
/usr/adm/ is /var/log/messages
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Other tasks:
# cleanup
(
find / -type f \( -name core -o -name a.out \
-o name dead.letter \) -atime +1 -exec rm -f {} \;
find /usr/spool/console -type f -mtime +7 -exec rm -f {} \;
find /usr/preserve -type f -mtime +15 -exec rm -f {} \;
find /usr/mail -type -f -atime +28 -exec rm -f {} \;
) > /dev/console 2>&1
! Performance Watch
- buffer cache hit ratios
- buffer cache write-behind ratio
- kernel time versus user time
- page wait
- page rate
- fullness of process table
- fullness of file table
- fullness of inode table
- fullness of clists
! User Administration
- making user directories
- creating password and group entries
- getting disk space
- taking care of all login functions
- handling group permissions
- changing ownerships and permissions
- moving users and user files
- updating YP data base source file
User password administration on multiple machines without YP requires the creation of a user-ID data base.
User-ID from 0 to 100 are reserved for non-humans, User-ID from 101 to 999 are system staff
! Identity Files – not enough info in passwd, group
- log name
- user ID number
- real name
- group
- group ID number
- phone number
- location
- department number
- misc
File Systems
Disks are split into partitions
A partition is then mounted as a subtree of the Unix directory structure
Example Configuration
Drive 0 Drive 1
/ root partition / 2n d root partition
/tmp temporary files /usr system libraries
swap space
/home user directories
- root partitions are small and near the outer edge of the drive to reduce risk of failure
- 2nd root partition to fix things if drive 0 fails (Harder without swap space)
- Essentials are kept on one drive (drive 0)
- /tmp can fill up and not interfere with /
- /tmp on different drive to user files to reduce disk head seeking when creating temporary files from user files
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