Quick Unixs Tips

Deleting Files by 'n' Dates
There are three times associated with a file
    atime  - last access time
    ctime  - last status change time
    mtime  - last modify time
To remove all files from directory /home/dpafumi that have ctime greater than 5 days, enter
find /home/dpafumi -type f -ctime +5 -exec rm {} \;
To test this, first use something like the above command to print out what files have a ctime greater than 5 days with
find /home/dpafumi -type f -ctime +5 -print
Both commands will go down recursively through subdirectories of /home/dpafumi.
To only go search /home/dpafumi, you have to use the GNU version of find
/usr/local/bin/find /home/dpafumi -type f -ctime +5 -maxdepth 1 -print


- How to find O/S VERSION or system name
        uname -ap

- Finding process id for trace or other process
         ps -fu username
- Zipping up a directory for backup
         1. zip -r file [Directory], or
         2. zip -r file *fresh* (This would zip up all files with fresh in the name, plus any directories, and all dirs underneath with fresh in the name
- How to tar a directory
         tar -cvf /tmp/filename *
         do this from the top direct ory that you want to bundle into the tar'd file
 - using 'tar' to list contents of tar file, without extracting
         tar -tvf [filename]
- Checking space on a disk
        df -tk
 Useful grep options
         grep -c  This counts the number of lines that contain the pattern
         grep -i  Ignore upper/lower case
         grep -l  Print only the name of the files that contain the pattern. Does not repeat file names.
- Count the number of files in a directory
         ls | wc -l
- How to send a message to everyone on a UNIX machine
         1. Create a file that contains the message
         2. $ wall < [filename] ( Ex: wall < message )
         3. You may need to specify the directory 'wall' is in. /usr/sbin/wall < message

 Removing some files to free up space
         1. Go to the destination directory
         2. Run 'find . -name "*.*O" -print'. Make sure this returns files you want to delete
         3. Run 'find . -name "*.*O" -exec rm -f {} \;
         WARNING! Make sure you do this right or you can remove more files that you want.
Find Memory in CPU
/usr/sbin/prtconf
or
dmesg | more

- How to do a search and replace in vi
          :%s,[string to replace], [replacing string], g
             example: :%s,oracle,stuck,gc {would replace oracle with stuck}
          The above command does this for the whole document without confirming, if
          you would like to confirm each change use the command:
             :%s,[string to replace], [replacing string], gc
          This will stop after each search, type a y to confirm the change

- Cleaning up memory and semaphores when a db process is killed, rather than being shut down via svrmgrl
          If a database process id is killed, rather than being shutdown properly via svrmgrl, then it will leave memonry and semaphores,
          which may prevent the db from being recreated. Do the following to clean it up.
          1. Run the UNIX command, 'ipcs -a'. You may want to stretch your screen as wide as it will go to get all the data returned to be on one line.
          2. Look for the line where the value for the column NATTCH is 0. This is the Memory for your killed process that you need to delete.
          3. Get the id# for that line from the ID column (first column)
          4. Run the command 'ipcrm -m id#' to delete this memory
          5. Figure out which line in the Semaphores zone is for your database.
          If there are multiple lines, you may be able to determine which one by comparing the value in the NSEMS column to value of 'processes=XX' in your init.ora.
          If only one line matches, then that is the line you need to delete.
          If you delete the wrong line you will crash someone else's database.
          If you cannot find a distinct line, you may want to try shutting down databases on the system until you can get one distinct line.
          Once the line is identified, you need to remove it also.
          6. Again, get the id# for that line from the first column.
          7. Run 'ipcrm -s id#

- To lock archive file for updating
         co -l tele.html


- Finding the IP address for different systems
         grep -i finsun /etc/hosts
- How to find the tcpip address for a machine
         nslookup [machine name]

Change the IP Address
METHOD 1
Open network configuration file. In this example, it’ll configure on interface eth0. Type
vi /etc/sysconfig/network-scripts/ifcfg-eth0

As an example, I'm showing that the current configuration is DHCP:
DEVICE=eth0
BOOTPROTO=dhcp
HWADDR=00:D0:B7:08:09:BB
ONBOOT=yes

Modify the file and perform the following modifications/additions (Change BOOTPROTO to static and add IP Address and Netmask as new lines if they’re not existed yet)
DEVICE=eth0
IPADDR=192.168.1.100
NETMASK=255.255.255.0
BOOTPROTO=static
HWADDR=00:D0:B7:08:09:BB
ONBOOT=yes
# The following settings are optional
BROADCAST=192.168.1.255   #Always Finish with 255
NETWORK=192.168.1.0       #Always Finish with 0
IPV6INIT=yes
IPV6_AUTOCONF=yes

Save and close the file. Define default gateway (router IP) and hostname in /etc/sysconfig//network file:
vi /etc/sysconfig/network

Append/modify configuration as follows:
NETWORKING=yes
HOSTNAME=machinename.domain.com
TYPE=Ethernet
GATEWAY=10.10.29.65

Save and close the file. Restart networking::
# /etc/init.d/network restart
or
# service network restart

Make sure you have correct DNS server defined in /etc/resolv.conf file:
# vi /etc/resolv.conf
Setup DNS Server as follows:
nameserver 10.0.80.11
nameserver 10.0.80.12
nameserver 202.67.222.222

Save and close the file. Now you can ping the gateway/other hosts:
$ ping 10.0.80.12
You can also check for Internet connectivity with nslookup or host command:
$ nslookup yahoo.com
Review the configuration. Type
ifconfig

METHOD 2You can also execute the following command from the X Window and it will show you the GUI Network Tool:
$ system-config-network &
METHOD 3If you don’t have X windows GUI installed type the following command at shell prompt:
# system-config-network-tui &



Change the HOST NAME
Make sure you are logged in as root and move to /etc/sysconfig and open the network file in vi.
cd /etc/sysconfig
vi network
Look for the HOSTNAME line and replace it with the new hostname you want to use. In this example I want to replace localhost with redhat9.
HOSTNAME=redhat9
When you are done, save your changes and exit vi. Next we will edit the /etc/hosts file and set the new hostname.
vi /etc/hosts


Finally we will restart the network to apply the changes we made to /etc/hosts and /etc/sysconfig/network.
service network restart