Tag: linux

How do I enable the UniRPC daemon?

Installation

  • Check /etc/services file for an existing entry:
grep 31438 /etc/services
  • If it doesn’t exist, add the necessary line to the /etc/services file manually, or using the commands below:
uvrpc           31438/tcp                       # uvNet rpc port
cp /etc/services /etc/services.`date +%Y%m%d.%H%M%S`
echo "uvrpc           31438/tcp                       # uvNet rpc port" >> /etc/services
  • Start the UniRPC daemon manually:
/u2/unishared/unirpc/unirpcd
  • The UniRPC daemon will start automatically on future boots from the main UniVerse startup script

Troubleshooting

  • Telnet to the local server on port 31438 and make sure there’s a response
[root@firestorm ~]# telnet localhost 31438
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.

^]
telnet> quit
Connection closed.
  • Check for the unirpcd process
ps -ef|grep unirpcd

How do I view my Eclipse tape backup logs on Linux?

The standard tape backup script keeps a number of log files that are accessible to the system administrator. To view the log files, log into your server as root and run the following commands. You may also configure the backup script to send an email every time the backup is run.

/tmp/backup.err contains the output from the tape backup command

cat /tmp/backup.err

The log for a successful tape backup will show output similar to the following, which indicates that 12 GB of data was backed up.

Total bytes written: 12501135360 (12GiB, 5.4MiB/s)

/tmp/backup.chk contains the start and stop timestamps for the tape backup operation

cat /tmp/backup.chk

The following log file indicates the backup ran for 30 minutes.

Backup started at: Mon Feb 22 21:00:05 EST 2010
Backup ended at: Mon Feb 22 21:30:11 EST 2010

/tmp/snapsave.log logs database suspension and snapshot operations:

cat /tmp/snapsave.log

This log file shows whether successful snapshot and/or backup processes took place, and details the database and snapshot operations taking place. This is very useful for troubleshooting backup issues.

The following excerpt from snapsave.log is an example of a successful tape backup:

Mon Dec 12 20:00:02 EST 2011: Starting tape backup to /dev/st0
Mon Dec 12 21:33:11 EST 2011: Checking Snapshot:
  LV       VG     Attr   LSize   Origin   Snap%  Move Log Copy%  Convert
  lvol0    datavg swi-ao 512.00M u2         6.73                        
  lvol1    datavg swi-ao   4.25G pdw        0.33                        
  lvol2    datavg swi-ao   5.76G eclipse    9.42                        
  lvol3    datavg swi-ao 512.00M ereports   0.21                        
Mon Dec 12 21:33:11 EST 2011: Ending tape backup to /dev/st0

How do I enable core dumps on Red Hat Enterprise Linux?

A core dump is a on disk representation of a state of a user space application at the time of its abnormal termination. Core dumps can be used to diagnose the cause of a crash of an application.

Core dumps are not useful to end users, as they require specialised skills to analyze and determine the cause of the crash. In most cases, enabling a core dump is not necessary until there is a specific need.

In Red Hat Enterprise Linux, core file creation is disabled for interactive shells. This is configured in the /etc/profile by theulimit command.

The /etc/profile contains system wide environment variables and commands that will be run for any interactive shell. By default, it contains this line:

ulimit -S -c 0 > /dev/null 2>1

To enable core dumps for interactive or non-daemon programs, change this line to:

ulimit -S -c unlimited  >/dev/null 2>1

This will allow all users to produce core files with no upper size limit.

Resources:

Why doesn’t Eterm look right when logged in as root on a Linux server?

Eterm uses a proprietary terminal emulation and does not transmit this information to the Linux server upon login. If you don’t manually set the terminal type, you will experience issues (vi won’t work, backspace will result in strange characters, etc.).

After logging in, type:

export TERM=vp60
Backspace will not work, but you can use CTRL-BACKSPACE or the LEFT ARROW keys at the login screen.

How do I reset my Linux server’s root password?

Reset Root Password

If a root password is forgotten, you can reset it:

  • Reboot the server
  • From the grub boot menu, select the kernel
  • Press the e key to edit the entry
  • Select second line (the line starting with the word kernel)
  • Press the e key to edit kernel entry so that you can append single user mode
  • Append the letter S (or word Single) to the end of the (kernel) line
  • Press ENTER key
  • Now press the b key to boot the Linux kernel into single user mode
  • You may need to mount at least / and other partitions:
mount -t proc proc /proc
mount -o remount,rw /
  • Change the root password, enter:
passwd

Finally reboot system:

sync
reboot