sys_nerr(3) [php man page]
PERROR(3) Linux Programmer's Manual PERROR(3) NAME
perror - print a system error message SYNOPSIS
#include <stdio.h> void perror(const char *s); #include <errno.h> const char * const sys_errlist[]; int sys_nerr; int errno; /* Not really declared this way; see errno(3) */ Feature Test Macro Requirements for glibc (see feature_test_macros(7)): sys_errlist, sys_nerr: Since glibc 2.19: _DEFAULT_SOURCE Glibc 2.19 and earlier: _BSD_SOURCE DESCRIPTION
The perror() function produces a message on standard error describing the last error encountered during a call to a system or library func- tion. First (if s is not NULL and *s is not a null byte (' ')), the argument string s is printed, followed by a colon and a blank. Then an error message corresponding to the current value of errno and a new-line. To be of most use, the argument string should include the name of the function that incurred the error. The global error list sys_errlist[], which can be 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[]. The use of sys_errlist[] is nowadays deprecated; use strerror(3) instead. 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 <errno.h>.) 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 system call or library function 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 immedi- ately followed by a call to perror(), the value of errno should be saved. ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7). +----------+---------------+---------------------+ |Interface | Attribute | Value | +----------+---------------+---------------------+ |perror() | Thread safety | MT-Safe race:stderr | +----------+---------------+---------------------+ CONFORMING TO
perror(), errno: POSIX.1-2001, POSIX.1-2008, C89, C99, 4.3BSD. The externals sys_nerr and sys_errlist derive from BSD, but are not specified in POSIX.1. NOTES
The externals sys_nerr and sys_errlist are defined by glibc, but in <stdio.h>. SEE ALSO
err(3), errno(3), error(3), strerror(3) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. 2017-09-15 PERROR(3)
Check Out this Related Man Page
PERROR(3) Linux Programmer's Manual PERROR(3) NAME
perror - print a system error message SYNOPSIS
#include <stdio.h> void perror(const char *s); #include <errno.h> const char * const sys_errlist[]; int sys_nerr; int errno; /* Not really declared this way; see errno(3) */ Feature Test Macro Requirements for glibc (see feature_test_macros(7)): sys_errlist, sys_nerr: Since glibc 2.19: _DEFAULT_SOURCE Glibc 2.19 and earlier: _BSD_SOURCE DESCRIPTION
The perror() function produces a message on standard error describing the last error encountered during a call to a system or library func- tion. First (if s is not NULL and *s is not a null byte (' ')), the argument string s is printed, followed by a colon and a blank. Then an error message corresponding to the current value of errno and a new-line. To be of most use, the argument string should include the name of the function that incurred the error. The global error list sys_errlist[], which can be 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[]. The use of sys_errlist[] is nowadays deprecated; use strerror(3) instead. 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 <errno.h>.) 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 system call or library function 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 immedi- ately followed by a call to perror(), the value of errno should be saved. ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7). +----------+---------------+---------------------+ |Interface | Attribute | Value | +----------+---------------+---------------------+ |perror() | Thread safety | MT-Safe race:stderr | +----------+---------------+---------------------+ CONFORMING TO
perror(), errno: POSIX.1-2001, POSIX.1-2008, C89, C99, 4.3BSD. The externals sys_nerr and sys_errlist derive from BSD, but are not specified in POSIX.1. NOTES
The externals sys_nerr and sys_errlist are defined by glibc, but in <stdio.h>. SEE ALSO
err(3), errno(3), error(3), strerror(3) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. 2017-09-15 PERROR(3)