NAME
       error - Generate an error

SYNOPSIS
       error message ?info? ?code?


DESCRIPTION
       Returns  a  TCL_ERROR  code,  which causes command interpretation to be
       unwound.  Message is a string that is returned to  the  application  to
       indicate what went wrong.

       If  the  info argument is provided and is non-empty, it is used to ini-
       tialize the global variable errorInfo.  errorInfo is used to accumulate
       a stack trace of what was in progress when an error occurred; as nested
       commands unwind, the Tcl interpreter adds information to errorInfo.  If
       the  info  argument  is present, it is used to initialize errorInfo and
       the first increment of unwind information will not be added by the  Tcl
       interpreter.   In other words, the command containing the error command
       will not appear in errorInfo; in its place will be info.  This  feature
       is most useful in conjunction with the catch command: if a caught error
       cannot be handled successfully, info can be  used  to  return  a  stack
       trace  reflecting  the original point of occurrence of the error: catch
       {...} errMsg set savedInfo $errorInfo ...  error $errMsg $savedInfo

       If the code argument is present, then its value is stored in the error-
       Code  global  variable.   This  variable is intended to hold a machine-
       readable description of the error in cases where  such  information  is
       available;  see  the  tclvars manual page for information on the proper
       format for the variable.  If the code argument  is  not  present,  then
       errorCode  is automatically reset to ``NONE'' by the Tcl interpreter as
       part of processing the error generated by the command.

EXAMPLE
       Generate an error if a basic mathematical operation fails: if  {1+2  !=
       3} {
           error "something is very wrong with addition" }


SEE ALSO
       catch(n), return(n), tclvars(n)


KEYWORDS
