unix

GNU Screen For Fun and Profit

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My friends and fellow virtualization professionals Tim Oudin & Joep Piscaer & Paul Gear and some commenters reminded me that the perfect complement to SSH session instability is the GNU utility ‘screen’. Indeed, I’ve been using it for years, and I recommend it to everybody doing any significant work in an SSH session. As the FSF puts it, “screen is a full-screen window manager that multiplexes a physical terminal between several processes, typically interactive shells.” In short, it virtualizes your interactive shell session so you can disconnect from it and reconnect to it as needed. On Linux hosts it usually comes as a package, else you can download it from gnu.org and compile it. I’ve built it on DEC UNIX and AIX in …

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Why I Don't Use Third-Party Binary Packages

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There are a number of third-party package repositories out there for Linux distributions. For example, Fedora runs the Extra Packages for Enterprise Linux (EPEL) repository, which contains builds of open source software that isn’t supplied with Fedora or Red Hat Enterprise Linux. Similarly, a lot of projects have their own repositories that supply builds of software for OpenSUSE, Debian, Ubuntu, etc. Maybe it’s just because I’m old-school, and maybe it’s because I enjoy compiling things, but I really don’t like the idea of using binaries found on the Internet. I never have. As an aside, I really tried hard to make the rest of this post not be critical, or seem like criticism, but instead just be a reflection of …

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UNIX Utility of the Day: watch

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Not a lot of people know about the ‘watch’ command, part of the standard complement of GNU tools available on most Linux distributions, as well as many Linux-like OSes such as VMware ESX and the VMware vMA. Simply put, it runs a command at a specific interval for you. So if you want to continually see the number of httpd processes running on a host you could use: watch ‘ps -ef | grep httpd | wc -l” Or maybe you want to watch the temperature on a remote physical host using IPMI. The -n flag changes the number of seconds between the commands: watch -n 60 -d ‘ipmitool -I lan -U username -P password -H host-bmc.address sdr type “Temperature”‘ The …

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