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PERROR !!!PERROR NAME SYNOPSIS DESCRIPTION CONFORMING TO SEE ALSO ---- !!NAME perror - print a system error message !!SYNOPSIS __#include __ __void perror(const char__ ''*s''__);__ __#include __ __const char *__''sys_errlist''__[[]; int__ ''sys_nerr''__;__ !!DESCRIPTION The routine __perror()__ produces a message on the standard error output, describing the last error encountered during a call to a system or library function. The argument string ''s'' is printed first, then a colon and a blank, then the message and a new-line. To be of most use, the argument string should include the name of the function that incurred the error. The error number is taken from the external variable ''errno'', which is set when errors occur but not cleared when non-erroneous calls are made. The global error list ''sys_errlist''[[] indexed by ''errno'' can be used to obtain the error message without the newline. The largest message number provided in the table is ''sys_nerr'' -1. Be careful when directly accessing this list because new error values may not have been added to ''sys_errlist''[[]. When a system call fails, it usually returns -1 and sets the variable ''errno'' to a value describing what went wrong. (These values can be found in ''''.) Many library functions do likewise. The function __perror()__ serves to translate this error code into human-readable form. Note that ''errno'' is undefined after a successful library call: this call may well change this variable, even though it succeeds, for example because it internally used some other library function that failed. Thus, if a failing call is not immediately followed by a call to __perror__, the value of ''errno'' should be saved. !!CONFORMING TO ANSI C, BSD 4.3, POSIX, X/OPEN !!SEE ALSO strerror(3) ----
5 pages link to
perror(3)
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rmt(8)
Man3p
errno(3)
psignal(3)
strerror(3)
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