Running SAS on Ubuntu Linux: Dash to Bash

It happened to me again today … the Ubuntu dash-bash-default-shell-thing:

userid@hostname:~$ /opt/sas92/SASFoundation/9.2/sas
/bin/sh: 0: Illegal option -p
userid@hostname:~$ /opt/sas93/SASFoundation/9.3/sas
/bin/sh: 0: Illegal option -p

I encounter this every now and then. This time I was upgrading my notebook and it’s Ubuntu 64-bit installation to 12.10 and restoring SAS 9.2 & 9.3 installations from backup.

Several years ago the default shell symlink of /bin/sh to /bin/bash was changed to /bin/dash in Ubuntu. You can find out more about the reasoning behind Ubuntu’s switch from bash to dash here – it caused quite a bit of discussion when it happened.

The often suggested fix is to manually change the /bin/sh symlink, but there’s also a command to do it (which also fixes the associated man page symlink too):

Continue reading “Running SAS on Ubuntu Linux: Dash to Bash”

SAS & JBoss: Too Many Open Files

I’ve been seeing some ‘Too many open files‘ exceptions in the SAS® mid-tier JBoss logs on my Ubuntu Linux server. I was surprised about this because I remember during installation I had followed the guidance in the SAS documentation and increased the nofile limit. It turns out that verifying the ulimit from a normal console/ssh login was not sufficient, I should have also verified it from an su based login too.

These were the sorts of messages I was seeing in the JBoss logs:

2012-03-11 09:22:38,463 ERROR [] Socket accept failed Too many open files
2012-03-11 08:57:19,454 ERROR [org.apache.catalina.core.StandardContext] Error reading tld listeners /opt/jboss-4.2.3.GA/server/SASServer3/work/jboss.web/localhost/SASBIDashboard/tldCache.ser (Too many open files)

There are some Pre-Installation Steps for JBoss for both SAS 9.3 and SAS 9.2 that should be followed during installation to avoid these errors. These were the instructions I had followed, but as you’ll see in a moment, it wasn’t quite enough for this (unsupported) Ubuntu installation.

The instructions specify to edit the /etc/security/limits.conf file directly. Rather than editing this main config file, where the settings might get forgotten or lost during an upgrade, I placed the settings I required for my SAS installation in their own dedicated config file: /etc/security/limits.d/sas.conf

# Increase the open file descriptors limit from the default of 1024 to 30720 for JBoss running web apps for SAS 9.2/9.3
* - nofile 30720

I knew that this had taken effect because I logged in, via ssh, to verify it as the sas user (I run JBoss as the sas user). Checking the ulimit I saw the following:

sas@server:~$ ulimit -Hn;ulimit -Sn

With nofile at 30270, how was it I was still getting ‘Too many open files‘ errors? After a quick session on Google I found a blog post suggesting the increased limits will only apply if the pam_limits PAM module is enabled.

Checking the /etc/pam.d/login file I could see the pam_limits line was already present and uncommented:
session required

This made sense since the console/ssh login showed the expected numbers.

Google also led me to a stackoverflow question (how do i set hard and soft file limits for a non-root user at boot?). The answer provided there indicated that, for su commands, you also need to verify the pam_limits module is enabled in an additional su specific PAM config file, which on my machine was /etc/pam.d/su. My JBoss init script runs as root during system startup but uses su to run JBoss as the sas user. Looking in /etc/pam.d/su I could see that the pam_limits line was commented so perhaps that was the issue.

Before making the necessary changes, I verified the nofile ulimit for the sas user by running su as root:

root@server:~# su sas --login --command 'ulimit -Hn;ulimit -Sn'

Aha! It had the 1024 default rather then the increased value. It looked like this was indeed the problem. I uncommented the pam_limits line in /etc/pam.d/su and repeated the test:

root@server:~# su sas --login --command 'ulimit -Hn;ulimit -Sn'

It now shows the increased value as expected, so it looks like the problem’s fixed. I restarted JBoss and haven’t seen any ‘Too many open files‘ errors since.

Desktop Files for Launching SAS Apps on Ubuntu

Whilst I often use the command line on Linux, it’s also nice to have icons in the menus to start SAS® applications like SAS Management Console and SAS Display Manager. These days I mostly use GNOME Do as an application launcher (its a bit like Quicksilver for Mac OS X). Naturally I like to be able to launch SAS apps from GNOME Do too. One day soon I’ll give Ubuntu Unity another try, and when I do eventually make the switch I probably wont use GNOME Do any more (but I’ll remember it as good friend), so then I’ll want to launch SAS apps from Unity. Thankfully I can use the same custom .desktop files in all of these situations.

Originally I used to point and click my way through editing the menus to add a custom launchers for SAS apps, but I soon tired of that. I’m a programmer too. Pointing and clicking doesn’t stay fun for long ;)

I found out about .desktop files after delving into what happened behind the scenes when I was editing the menus using point and click methods. There’s a GNOME Dev Center tutorial on it “Desktop files: putting your application in the desktop menus“. The site also has a list of the Recognized desktop entry keys that can go into a .desktop file.

Below are some of the .desktop files that I use to launch SAS applications on my Ubuntu installation. I have only tested these on Ubuntu using GNOME but, since they are standard freedesktop files, I imagine they should also work in KDE and other Linux distros.

If you place the .desktop files into the ~/.local/share/applications directory (e.g. /home/userid/.local/share/applications) they will only be available to that single user. Alternatively, if they are placed into the /usr/share/applications directory then they will be available to all users.

The nice thing I have found about editing .desktop files is, so far at least, the changes have shown up in the menus immediately (i.e. without having to logout/login). In my installation the menu entries for these .desktop files can be found in the Ubuntu Applications > Other menu. They show up in GNOME Do too.

Here are the .desktop files I use:

SAS Management Console 9.2

This is a sas-mc-92.desktop file that I use to launch SAS Management Console 9.2 on Ubuntu.

#!/usr/bin/env xdg-open

[Desktop Entry]
Name=SAS Management Console 9.2

SAS 9.2 Display Manager

This is a sas-dms-9.2.desktop file that I (sometimes) use to launch the old SAS Display Manager System (DMS) interface on Ubuntu. If you’ve used DMS on Linux you’ll probably understand why I only use it sometimes ;). I’d love to have a native SAS Enterprise Guide like interface to SAS on Linux (without having to start Windows in VirtualBox). I know, given the numbers, it’s unlikely to ever happen, but I can’t help wishing nonetheless :).

#!/usr/bin/env xdg-open

[Desktop Entry]
Name=SAS Display Manager 9.2

You wont find the /usr/local/SAS/sas-logo-48×48.png file in your installation so you should substitute that with the path to an appropriate icon available in your installation.

SAS Management Console 9.1

This is a sas-mc-913.desktop file that I use to launch SAS Management Console 9.1 on Ubuntu.

#!/usr/bin/env xdg-open

[Desktop Entry]
Name=SAS Management Console 9.1

If you are a SAS user on Linux then I hope you find these useful too. If you have any info/experiences to share regarding .desktop files launching SAS apps in other desktop environments (KDE, Xfce etc.) or other distros (RHEL, Fedora etc.) then please leave a comment.

Disabling the Ubuntu Login Screen (GDM) User Pick List

I’m used to typing in both my userid and my password when I log in to computers. I have never been a fan of the user pick lists that now seem to be common to many operating systems. I can see how they can be convenient for family machines at home, but the idea of advertising a list of potential accounts to compromise doesn’t sit well with me, so my preference is to disable the pick list and go back to the traditional typed userid & password form.

I run SAS on Ubuntu and recent Ubuntu versions (I forget which one it started with) now have a user pick list by default. The method for disabling the user pick list in Ubuntu is not that obvious and I find myself googling it every time I need it. A good article that provides both command line and GUI methods of disabling the user list can be found at Disabling the Login Screen User List in Ubuntu

The command line version is:

sudo -u gdm gconftool-2 --set --type boolean /apps/gdm/simple-greeter/disable_user_list true

This can be followed by a quick restart of GDM:

restart gdm

.. and the user pick list is no more.

With Lucid (Ubuntu 10.04 LTS) there is still a redundant login button that needs to be clicked before you get to type your user id, but it’s still better than before. There has been a bug lodged for this behaviour (GDM without user list requires that you click Log In) and it appears to have been fixed so I look forward to seeing it when I next upgrade.

Sudo with no password prompt

DISCLAIMER: This is definitely not recommended for any type of real environment that you rely on to be secure, but sometimes when you are setting up demo/sandpit/throwaway environments you want to be able to execute commands on Linux as root using sudo without getting prompted for your password. You could just work in a root shell all the time, but perhaps you still want to use sudo so you can use your normal account mostly and save yourself from potential accidents by only using sudo when you have to.

So, disclaimer out of the way, here’s how you can set yourself up as a no-password-sudoer (assuming you start out with sudo/root access to begin with):

Add your userid to an appropriate admin group:
sudo gpasswd -a youruserid youradmingroup

Edit the sudoers file:
sudo visudo

… to add an entry to allow your admin group to execute any command via sudo with no password requirement:
%youradmingroup ALL=NOPASSWD: ALL

BTW – visudo on Ubuntu defaults to the nano editor. If you prefer vi/vim you can switch default editor with:

sudo update-alternatives --config editor

.. and select the /usr/bin/vim.basic entry.

There’s more info about sudo on Ubuntu in the community documentation: RootSudo, Sudoers and RootSudoTimeout.

That’s it… sometimes handy but also dangerous … don’t say I didn’t warn you ;)