83 lines
3.4 KiB
Plaintext
83 lines
3.4 KiB
Plaintext
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Why does "ps -aux" complain about a bogus '-'?
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According to the POSIX and UNIX standards, the above command asks to display
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all processes with a TTY (generally the commands users are running) plus all
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processes owned by a user named "x". If that user doesn't exist, then ps will
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assume you really meant "ps aux". The warning is given to gently break you of a
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habit that will cause you trouble if a user named "x" were created.
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Why don't I see SMP (per-CPU) stats in top?
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You didn't enable it. Press '?' for built-in help or read the man page. Per-CPU
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stats are disabled by default because they take up too much space. Some Linux
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systems have hundreds of CPUs.
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Why do long usernames get printed as numbers?
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The UNIX and POSIX standards require that user names and group names be printed
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as decimal integers when there is not enough room in the column. Truncating the
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names, besides being a violation of the standard, would lead to confusion
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between names like MichelleRichards and MichelleRichardson. The UNIX and POSIX
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way to change column width is to rename the column:
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ps -o pid,user=CumbersomeUserNames -o comm
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The easy way is to directly specify the desired width:
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ps -o pid,user:19,comm
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Why is %CPU underreported for multi-threaded (Java, etc.) apps?
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You need to upgrade to the 2.6.10 kernel at least. Older kernels do not provide
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a reasonable way to get this information.
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Why do ps and top show threads individually?
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The 2.4.xx kernel does not provide proper support for grouping threads by
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process. Hacks exist to group them anyway, but such hacks will falsely group
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similar tasks and will fail to group tasks due to race conditions. The hacks
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are also slow. As none of this is acceptable in a critical system tool, task
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grouping is not currently available for the 2.4.xx kernel. The 2.6.xx kernel
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allows for proper thread grouping and reporting. To take advantage of this,
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your programs must use a threading library that features the CLONE_THREAD flag.
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The NPTL pthreads provided by recent glibc releases use CLONE_THREAD.
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What systems are supported?
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Linux 2.4.xx and 2.6.xx are commonly tested and expected to work well. SMP is
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well supported. Multi-node cluster views require a multi-node /proc filesystem;
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without that you will see a single-node view.
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Where to I send bug reports?
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You may use the Debian bug tracking system or send your report to
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procps-feedback@lists.sf.net (no subscription required) instead.
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Why are there so many procps projects?
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The original maintainer seems to have had little time for procps. Whatever his
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reasons, the project didn't get maintained. Starting in 1997, Albert Cahalan
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wrote a new ps program for the package. For the next few years, Albert quietly
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helped the Debian package maintainer fix bugs. In 2001, Rik van Riel decided to
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do something about what appeared to be the lack of a maintainer. He picked up
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the buggy old code in Red Hat's CVS and started adding patches. Meanwhile,
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other people have patched procps in a great many ways. In 2002, Albert moved
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procps to this site. This was done to ensure that years of testing and bug
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fixes would not be lost. The major version number was changed to 3, partly to
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avoid confusing users and partly because the top program has been redone.
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Why does ps get signal 17?
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No ps release has ever had this problem. Most likely your system has been
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broken into. You might want to install a more recent version of the OS. If
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you'd rather take your chances, simply upgrade procps.
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