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32 .\" @(#)strerror.3 8.1 (Berkeley) 6/9/93
45 .Nd system error messages
51 .Fn perror "const char *string"
52 .Vt extern const char * const sys_errlist[] ;
53 .Vt extern const int sys_nerr ;
56 .Fn strerror "int errnum"
58 .Fn strerror_l "int errnum" "locale_t"
60 .Fn strerror_r "int errnum" "char *strerrbuf" "size_t buflen"
68 functions look up the error message string corresponding to an
73 function accepts an error number argument
75 and returns a pointer to the corresponding message string
76 in the current locale.
79 It returns a pointer to an internal static buffer that could be
82 call from another thread.
90 locale handle arguments and returns a pointer to a string
91 corresponding to the specified error in the given locale.
93 is thread-safe, its result can be only overwritten by
96 from the current thread.
100 function renders the same result into
104 characters and returns 0 upon success.
108 function finds the error message corresponding to the current
109 value of the global variable
112 and writes it, followed by a newline, to the
113 standard error file descriptor.
118 and does not point to the null character,
119 this string is prepended to the message
120 string and separated from it by
123 otherwise, only the error message string is printed.
125 If the error number is not recognized, these functions return an error message
127 .Dq Li "Unknown error:\ "
128 followed by the error number in decimal.
136 Error numbers recognized by this implementation fall in
141 The number 0 is also recognized, although applications that take advantage of
142 this are likely to use unspecified values of
145 If insufficient storage is provided in
149 to contain the error string,
155 will contain an error message that has been truncated and
157 terminated to fit the length specified by
160 The message strings can be accessed directly using the external
165 contains a count of the messages in
167 The use of these variables is deprecated;
172 should be used instead.
174 The following example shows how to use
177 .Bd -literal -offset 2n
187 if ((fd = open("/nonexistent", O_RDONLY)) == -1) {
191 printf("File descriptor: %d\en", fd);
196 When executed, the program will print an error message along the lines of
197 .Ql "open(): No such file or directory" .
222 functions first appeared in
226 function was implemented in
229 .An Wes Peters Aq Mt wes@FreeBSD.org .
232 function was added in
237 function returns its result in a static buffer which
238 will be overwritten by subsequent calls.
240 Programs that use the deprecated
242 variable often fail to compile because they declare it
246 object might increase during FreeBSD lifetime,
247 breaking some ABI stability guarantees.