.TH PERROR 3F
.UC
.SH NAME
perror, gerror, ierrno \- get system error messages
.SH SYNOPSIS
.B subroutine perror (string)
.br
.B character*(*) string
.sp 1
.B subroutine gerror (string)
.br
.B character*(*) string
.sp 1
.B character*(*) function gerror()
.sp 1
.B function ierrno()
.SH DESCRIPTION
.I Perror
will write a message to fortran logical unit 0
appropriate to the last detected system error.
.I String
will be written preceding the standard error message.
.PP
.I Gerror
returns the system error message in character variable
.I string.
.I Gerror
may be called either as a subroutine or as a function.
.PP
.I Ierrno
will return the error number of the last detected system error.
This number is updated only when an error actually occurs.
Most routines and I/O statements that might generate such errors
return an error code after the call;
that value is a more reliable indicator of what caused the error condition.
.SH FILES
.ie \nM /usr/ucb/lib/libU77.a
.el /usr/lib/libU77.a
.SH "SEE ALSO"
intro(2), perror(3), ``Introduction to the f77 I/O Library''
.SH BUGS
.I String
in the call to
.I perror
can be no longer than 127 characters.
.PP
The length of the string returned by
.I gerror
is determined by the calling program.
.SH NOTES
UNIX system error codes are described in
.IR intro (2).
The f77 I/O error codes and their meanings are:
.sp 1
.in +5
100	``error in format''
.br
101	``illegal unit number''
.br
102	``formatted io not allowed''
.br
103	``unformatted io not allowed''
.br
104	``direct io not allowed''
.br
105	``sequential io not allowed''
.br
106	``can't backspace file''
.br
107	``off beginning of record''
.br
108	``can't stat file''
.br
109	``no * after repeat count''
.br
110	``off end of record''
.br
111	``truncation failed''
.br
112	``incomprehensible list input''
.br
113	``out of free space''
.br
114	``unit not connected''
.br
115	``read unexpected character''
.br
116	``blank logical input field''
.br
117	``'new' file exists''
.br
118	``can't find 'old' file''
.br
119	``unknown system error''
.br
120	``requires seek ability''
.br
121	``illegal argument''
.br
122	``negative repeat count''
.br
123	``illegal operation for unit''