Using Linux and DOS Together
I found it effective to use loadlin, a DOS-based loader; this has the distinct advantage of always booting a working system before running Linux. My experience with LILO has been if you don't do it right, your system is only useful as a paper weight. In my MS-DOS config.sys, I take advantage of the menus, and the result is shown in Listing 1.
menuitem=dos menuitem=simple.dos menuitem=linux.1.2.8 menuitem=scandisk menudefault=linux.1.2.8,5 [linux.1.2.8] SHELL=C:\loadlin\loadlin.exe \loadlin\zimage.128 root=/dev/hdc2 -v ro [simple.dos] [dos] DEVICE=C:\DOS\HIMEM.SYS DEVICEHIGH=C:\MAGICS20\CDIFINIT.SYS /T:X DEVICEHIGH=C:\MTM\MTMCDAI.SYS /D:MTMIDE01 DEVICEHIGH /L:2,12048 =C:\DOS\SETVER.EXE DOS=HIGH STACKS=9,256 [scandisk] SHELL=c:\dos\scandisk.exe /all /checkonly
I boot Linux with a delay of 5 seconds, the advantage being that the system can always boot DOS and will work in some capacity. I find this preferable to using LILO and modifying the master boot record on your hard disk (if you do anything wrong, you need to boot from floppy to recover).
One can easily select several kernels and/or configurations from the command line. Using loadlin, you have to make a compressed kernel (make zImage), and then put it on a DOS partition. I find this strategy effective even when installing Linux the first time (instead of dealing with a boot and root floppy, the system can boot the kernel with only a root floppy needed). You can easily add to the menu to have several different kernels to boot from. Remember, you can use the rdev utility to build defaults (like the root device) into the kernel.
In your autoexec.bat you can use the strategy:
goto %config% :simple.dos PATH=C:\marty\bin;C:\gnu\bin;C:\dos;C:\ goto end :dos SET SOUND16=C:\MAGICS20 C:\MAGICS20\SNDINIT /b SET BLASTER=A220 I7 D1 T4 C:\DOS\SMARTDRV.EXE 512 512 /C C:\DOS\IMOUSE.COM PROMPT $p$g SET PATH=c:\gnu\bin;C:\MARTY\BIN;C:\WINDOWS;C:\DOS; SET TEMP=C:\DOS JOIN d: \marty JOIN f: \gnu goto end :end
The simple.dos setting is conceptually the same as booting Linux in single user mode. I find it very useful for debugging a DOS system. If you want, you can add config.sys menu entries to boot different kernels, boot Linux in single user mode, boot Linux from floppies, etc.
In the standard Linux kernel configuration, the UMSDOS file system isn't enabled. UMSDOS has a number of major advantages if you need file systems to be shared between Linux and DOS. It retains full Unix semantics, so you don't have to always be handicapped by DOS problems such as:
lack of links
restrictions of 8+3 file naming conventions
restrictions of characters in file names
one date (instead of access/change/modify time)
lack of owner/groups
Using UMSDOS you can take advantage of a file system shared between DOS and Linux, with the appearance of being a Linux file system when you run Linux. If you want files to be portable between MS-DOS and Linux, restrict yourself to DOS filenames (8+3 characters). Don't use links if you want the files to appear under DOS. With a Linux file system, it's easy do things like create “dot files”, do gzip-r on trees, and create links and backup files. Any file is readable in MS-DOS; however, if you don't conform to the MS-DOS file naming conventions, files are “munged” (that is, their names are squeezed to fit within the 8+3 namespace). This munging is similar to what happens in mfs; those who use PC-NFS are probably familiar with this.
When you start running the UMSDOS file systems, remember to run the application called umssync, which creates consistency between the --linux-.--- files and the directory contents. You can have problems if you add or delete files under DOS without Linux knowing about it. Call umssync from /etc/rc.d/rc.local or /etc/rc.d/rc.M after the mount takes place, and this shouldn't be a problem.
I've noticed a problem in UMSDOS files systems—the mount points are owned by root, only writable by root, and the date is the beginning of the epoch. A simple workaround is after mounting, do chown/chmod to the mount points as appropriate (in your /etc/rc.d/rc.local file. Also, I find it useful to occasionally run scandisk from DOS (notice the scandisk target in config.sys).
There is a performance penalty for DOS and UMSDOS file systems compared to normal ext2. The penalty becomes severe if you have several hundred files in a single directory (when you do an ls, get a cup of coffee). What I've noticed is sequential I/O (with a tester called Bonnie) is marginally faster on ext2 than UMSDOS.
But UMSDOS is ideal if you're doing work with DOSEMU. You put DOS files on UMSDOS partitions, and you can easily access them from DOS, DOSEMU or Linux. If they keep within the DOS file system bounds of 8+3 characters, they look the same on both DOS and Linux. UMSDOS partitions provide a big advantage when sharing files with DOS (much more so then the MSDOS file system, since it treats Linux files as Linux files), but performance has to be watched.
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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- Stunnel Security for Oracle
- My +1 Sword of Productivity
- SUSE LLC's SUSE Manager
- Non-Linux FOSS: Caffeine!
- Managing Linux Using Puppet
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Parsing an RSS News Feed with a Bash Script
- Google's SwiftShader Released
- Doing for User Space What We Did for Kernel Space
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide