1ERR(3)                     Linux Programmer's Manual                    ERR(3)
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NAME

6       err,  verr,  errx,  verrx, warn, vwarn, warnx, vwarnx - formatted error
7       messages
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SYNOPSIS

10       #include <err.h>
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12       noreturn void err(int eval, const char *fmt, ...);
13       noreturn void errx(int eval, const char *fmt, ...);
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15       void warn(const char *fmt, ...);
16       void warnx(const char *fmt, ...);
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18       #include <stdarg.h>
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20       noreturn void verr(int eval, const char *fmt, va_list args);
21       noreturn void verrx(int eval, const char *fmt, va_list args);
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23       void vwarn(const char *fmt, va_list args);
24       void vwarnx(const char *fmt, va_list args);
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DESCRIPTION

27       The err() and warn() family of functions display a formatted error mes‐
28       sage on the standard error output.  In all cases, the last component of
29       the program name, a colon character, and a space are  output.   If  the
30       fmt argument is not NULL, the printf(3)-like formatted error message is
31       output.  The output is terminated by a newline character.
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33       The err(), verr(), warn(), and vwarn() functions append an  error  mes‐
34       sage obtained from strerror(3) based on the global variable errno, pre‐
35       ceded by another colon and space unless the fmt argument is NULL.
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37       The errx() and warnx() functions do not append an error message.
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39       The err(), verr(), errx(), and verrx() functions  do  not  return,  but
40       exit with the value of the argument eval.
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ATTRIBUTES

43       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
44       tributes(7).
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46       ┌─────────────────────────────────────┬───────────────┬────────────────┐
47       │Interface                            │ Attribute     │ Value          │
48       ├─────────────────────────────────────┼───────────────┼────────────────┤
49       │err(), errx(), warn(), warnx(),      │ Thread safety │ MT-Safe locale │
50       │verr(), verrx(), vwarn(), vwarnx()   │               │                │
51       └─────────────────────────────────────┴───────────────┴────────────────┘
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CONFORMING TO

54       These functions are nonstandard BSD extensions.
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EXAMPLES

57       Display the current errno information string and exit:
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59           p = malloc(size);
60           if (p == NULL)
61               err(EXIT_FAILURE, NULL);
62           fd = open(file_name, O_RDONLY, 0);
63           if (fd == -1)
64               err(EXIT_FAILURE, "%s", file_name);
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66       Display an error message and exit:
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68           if (tm.tm_hour < START_TIME)
69               errx(EXIT_FAILURE, "too early, wait until %s",
70                       start_time_string);
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72       Warn of an error:
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74           fd = open(raw_device, O_RDONLY, 0);
75           if (fd == -1)
76               warnx("%s: %s: trying the block device",
77                       raw_device, strerror(errno));
78           fd = open(block_device, O_RDONLY, 0);
79           if (fd == -1)
80               err(EXIT_FAILURE, "%s", block_device);
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SEE ALSO

83       error(3), exit(3), perror(3), printf(3), strerror(3)
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COLOPHON

86       This  page  is  part of release 5.12 of the Linux man-pages project.  A
87       description of the project, information about reporting bugs,  and  the
88       latest     version     of     this    page,    can    be    found    at
89       https://www.kernel.org/doc/man-pages/.
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93Linux                             2021-03-22                            ERR(3)
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