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6. Solutions to common miscellaneous problems.

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6.1 free dumps core.

In Linux 1.3.57 and later the format of /proc/meminfo was changed in a way that the implementation of free doesn't understand.

Get the latest version, from sunsite.unc.edu in /pub/Linux/system/Status/ps/procps-0.99.tgz.

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6.2 My clock is very wrong.

There are two clocks in your computer. The hardware (CMOS) clock runs even when the computer is off and is used to when the system starts up and by DOS (if you use it). The ordinary system time, shown and set by date, is maintained by the kernel while Linux is running.

You can display the CMOS clock time, or set either clock from the other, with /sbin/clock program - see man 8 clock.

There are various other programs that can correct either or both clocks for systematic drift or transfer time across the network. Some of them may already be installed on your system. Try looking at or for adjtimex (corrects for drift), netdate and getdate (simply get the time from the network) or xntp (accurate fully-featured network time daemon).

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6.3 Setuid scripts don't seem to work.

That's right. This feature has been deliberately disabled in the Linux kernel because setuid scripts are almost always a security hole. If you want to know why read the FAQ for comp.unix.questions.

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6.4 Free memory as reported by free keeps shrinking.

The `free' figure printed by free doesn't include memory used as a disk buffer cache - shown in the `buffers' column. If you want to know how much memory is really free add the `buffers' amount to `free' - newer versions of free print an extra line with this info.

The disk buffer cache tends to grow soon after starting Linux up, as you load more programs and use more files and the contents get cached. It will stabilise after a while.

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6.5 When I add more memory it slows to a crawl.

This is quite a common symptom of a failure to cache the additional memory. The exact problem depends on your motherboard.

Sometimes you have to enable caching of certain regions in your BIOS setup. Look in the CMOS setup and see if there is an option to cache the new memory area which is currently switched off. This is apparently most common on a 486.

Sometimes the RAMs have to be in certain sockets to be cached.

Sometimes you have to set jumpers to enable the caching.

Some motherboards don't cache all the RAM if you have more RAM per amount of cache than they expect. Usually a full 256K cache will solve this problem.

If in doubt, check your motherboard manual. If you still can't fix it because the documentation is inadequate you might like to post a message to comp.os.linux.hardware giving *all* the details - make, model number, date code, etc. so that other Linux users can avoid it.

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