version 1, including all changes.
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perry |
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PERROR |
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!!!PERROR |
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NAME |
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SYNOPSIS |
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DESCRIPTION |
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CONFORMING TO |
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SEE ALSO |
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---- |
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!!NAME |
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perror - print a system error message |
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!!SYNOPSIS |
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__#include __ |
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__void perror(const char__ |
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''*s''__);__ |
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__#include __ |
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__const char *__''sys_errlist''__[[]; |
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int__ ''sys_nerr''__;__ |
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!!DESCRIPTION |
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The routine __perror()__ produces a message on the |
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standard error output, describing the last error encountered |
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during a call to a system or library function. The argument |
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string ''s'' is printed first, then a colon and a blank, |
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then the message and a new-line. To be of most use, the |
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argument string should include the name of the function that |
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incurred the error. The error number is taken from the |
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external variable ''errno'', which is set when errors |
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occur but not cleared when non-erroneous calls are |
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made. |
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The global error list ''sys_errlist''[[] indexed by |
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''errno'' can be used to obtain the error message without |
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the newline. The largest message number provided in the |
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table is ''sys_nerr'' -1. Be careful when directly |
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accessing this list because new error values may not have |
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been added to ''sys_errlist''[[]. |
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When a system call fails, it usually returns -1 and sets the |
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variable ''errno'' to a value describing what went wrong. |
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(These values can be found in ''''.) Many |
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library functions do likewise. The function __perror()__ |
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serves to translate this error code into human-readable |
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form. Note that ''errno'' is undefined after a successful |
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library call: this call may well change this variable, even |
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though it succeeds, for example because it internally used |
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some other library function that failed. Thus, if a failing |
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call is not immediately followed by a call to __perror__, |
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the value of ''errno'' should be saved. |
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!!CONFORMING TO |
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ANSI C, BSD 4.3, POSIX, X/OPEN |
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!!SEE ALSO |
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strerror(3) |
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---- |
