How To: Confirm Link Speed for a Network Interface

Here’s a one liner that is really useful when you need to quickly confirm the link speed for network interfaces on your system.

The beauty of this command is that you can run it as a regular user:

bash-3.00$ kstat -p | grep link_speed
 e1000g:0:Port Stats:link_speed 1000
 e1000g:1:Port Stats:link_speed 1000

Using nohup for existing processes

Most of you are probably aware with the fact that by default any processes you may have running within your session will be killed once you terminate the session. The most common example is logging onto a remote server via SSH, starting some command and then closing the terminal session.

As you know, this happens because when your’e terminating your shell it ends up sending the SIGHUP signal to all the child processes, notifying them about the end of the session and therefore instructing them to wrap up whatever it was they were doing and to terminate.

Many are also aware of the wonderful nohup command which adds flexibility to start any command in a mode where it will ignore the SIGHUP and therefore stay running (and writing output to log files, for example) even after your terminal session completes.

Basic usage of the nohup command

Here’s how you should use it:

$ nohup ./massive-job.sh &
Sending output to nohup.out
[1] 3763

What this does is put your massive-job.sh script into background while making it ignore SIGHUP signals in the past. The background element is not necessary but very common because if you expect something to be running for hours/days – you probably don’t want to be watching it in your terminal anyway. So you put the task into background.

The [1] indicates that this is the first (and only) job you’re running in background so far. The 3763 is the process ID (PID) of the massive-job.sh script.

Output redirection into nohup.out

nohup command redirects all the standard input into nohup.out file so if you’re interested in your script’s output you can still keep an eye on it this way:

tail -f nohup.out

nohup for an existing process

In recent versions of Solaris 10 the nohup command has seen a really welcomed addition: it now allows you to make any process (within your privileges of course) ignore SIGHUP signal. This is really convenient because if you started some script in the morning and by late afternoon it’s obvious that it won’t finish by the time you should be heading home – you can now simply use nohup command to update the process and allow it to finish even when you log out.

Another reason it’s so convenient is because prior to this feature the scenario described above would leave you no option but to keep your session open. If you couldn’t (for example you must disconnect your laptop every evening) – you had to stop the script and restart next morning (with nohup this time).

Here’s how you update an existing process:

-bash-4.1# nohup -p 3468
Sending output to nohup.out

or get a message suggesting you must elevate your privileges before you can do it:

greys@solaris:~$ nohup -p 3468
nohup: cannot examine 3468: permission denied

Using Service Controller to confirm battery status

I’ve been working with a support engineer on replacing an SC battery in one of T2000 servers recently, and noticed that immediately upon rebooting a server it may not be possible to get battery and fans stats because prtdiag command wouldn’t work (picld daemon not fully operating yet).

Turns out, there’s another way to get this info – simply use #. to get back into ALOM and run the showevnironment command. Among other things, it reports battery status:

sc> showenvironment
...
--------------------------------------------------------------------------------
Voltage sensors (in Volts):
--------------------------------------------------------------------------------
Sensor          Status      Voltage LowSoft LowWarn HighWarn HighSoft
--------------------------------------------------------------------------------
MB/V_+1V5       OK            1.48    1.36    1.39    1.60     1.63
MB/V_VMEML      OK            1.79    1.63    1.67    1.92     1.98
MB/V_VMEMR      OK            1.79    1.63    1.67    1.92     1.98
MB/V_VTTL       OK            0.89    0.81    0.83    0.96     0.99
MB/V_VTTR       OK            0.87    0.81    0.83    0.96     0.99
MB/V_+3V3STBY   OK            3.33    3.13    3.16    3.53     3.59
MB/V_VCORE      OK            1.31    1.20    1.24    1.36     1.39
IOBD/V_+1V5     OK            1.48    1.36    1.39    1.60     1.63
IOBD/V_+1V8     OK            1.79    1.63    1.67    1.92     1.96
IOBD/V_+3V3MAIN OK            3.36    3.06    3.10    3.49     3.53
IOBD/V_+3V3STBY OK            3.33    3.13    3.16    3.53     3.59
IOBD/V_+1V      OK            1.18    1.09    1.11    1.28     1.30
IOBD/V_+1V2     OK            1.16    1.09    1.11    1.28     1.30
IOBD/V_+5V      OK            5.09    4.55    4.75    5.35     5.45
IOBD/V_-12V     OK          -12.11  -13.08  -12.84  -11.16   -10.92
IOBD/V_+12V     OK           12.06   10.92   11.16   12.84    13.08
SC/BAT/V_BAT    OK            3.37      --    2.25      --       --

prstat – a great tool for process monitoring

Solaris administrators with solid Linux experience are usually installing top on their systems because of convenience. Quite a few administrators are aware of prstat but don't see benefits of using its format which somewhat differs from top. And a really small number of Solaris sysadmins really know how to use the prstat command properly. I consider myself a power user, so won't even be claiming to be a prstat guru, but these command examples will hopefully teach you a thing or two.

 

prstat advantages at glance

I really like prstat because it gives me access to the following information:

  • microstate accounting with LOTS of CPU info
  • CPU usage stats across global and non-global zones
  • provide reports (multiple screens of stats taken at specific intervals) forwarded to a file
  • do really useful summaries about top users consuming your OS resources

inetadm – changing service properties

Today I’ve met a problem which I easily solved with the help of inetadm, and here’s the entry explaining what happened.

When trying to FTP some files off my laptop, I’ve noticed FTP client failing to parse the ls -l output due to Russian weekdays used in listing. It was obvious that such FTP daemon behavior was due to one of its options, which specifically made sure the daemon inherited all the environment variables. Luckily such a behavior was easy to change with inetadm:

[Read more…]

What would we do without crle?

While compiling some of the stuff I use in 64bit lately, I’ve had another chance to use the wonderful crle tool and to acknowledge once again just how easier it made my life.

Here’s what you can read from man crle:

The crle utility provides for the creation and display of a
runtime linking configuration file. The configuration file
is read and interpreted by the runtime linker, ld.so.1(1),
during process start-up.

The tool does exactly that – it specifies where ld should look first for the necessary libraries as you start any executable.

[Read more…]