error - Analyzes and disperses compiler error messages
error [-n] [-q] [-s] [-v] [-t suffix_list] [-I ignore_file] [file]
The error program analyzes and optionally disperses the diagnostic error
messages produced by a number of compilers and language processors to the
source file and line where the errors occurred.
Takes the names of functions to ignore from ignore_file. If the -I
option is not specified, the function names are taken from a file named
.errorrc in the user's home directory. If this file does not exist, no
error messages are nullified. Function names must be listed one per
line in ignore_file or in the .errorrc file.
-n Does not touch any files; all error messages are sent to the standard
-q Queries the user whether or not to touch the file. You must enter y or
n, or the locale's equivalent of an affirmative or negative response,
before continuing. If you do not specify the -q option, all referenced
files (except those referring to discarded error messages) are touched
-s Prints out statistics regarding the error categorization.
Does not touch files whose suffixes do not appear suffix_list. The suf-
fix list is dot-separated, and * wildcards may be used. For example,
the suffix list .c.y.foo*.h allows error to touch files ending with .c,
.y, .foo* and .y.
-v Overlays and sets up the visual editor vi to edit all files touched,
and positions the editor at the first error in the first touched file.
If vi cannot be found, try ex or ed from standard places.
Using the error program can replace the painful, traditional methods of
scribbling abbreviations of errors on paper, and permits error messages and
source code to be viewed simultaneously without machinations of multiple
windows in a screen editor.
The error program looks at the error messages, either from the specified
file file or from the standard input, and performs the following opera-
+ Attempts to determine which language processor produced each error
+ Determines the source file and line number to which the error message
+ Determines if the error message is to be ignored or not.
+ Inserts the (possibly slightly modified) error message into the source
file as a comment on the line preceding to which the line the error
+ Sends error messages that cannot be categorized by language processor
or content to the standard output; does not insert these error mes-
sages into any file.
The error program touches source files only after all input has been read.
The error program is intended to be run with its standard input connected
via a pipe to the error message source. Some language processors put error
messages on their standard error file; others put their messages on the
standard output. Hence, both error sources should be piped together into
error. For example, when using the csh syntax, the following command line
analyzes all the error messages produced by whatever programs make runs
when making lint:
make -s lint | error -q -v
The error program knows about the error messages produced by the following
The error program knows a standard format for error messages produced by
the language processors, so is sensitive to changes in these formats. For
all languages except Pascal, error messages are restricted to be on one
line. Some error messages refer to more than one line in more than one
file; error duplicates the error message and inserts it at all of the
The error program does one of six things with error messages:
Some language processors produce short errors describing which file it
is processing. The error program uses these to determine the file name
for languages that do not include the file name in each error message.
These synchronization messages are consumed entirely by error.
Error messages from lint that refer to one of the two lint libraries,
/usr/libdata/lint/llib-lc and /usr/libdata/lint/llib-port are dis-
carded, to prevent accidentally touching these libraries. Again, these
error messages are consumed entirely by error.
Error messages from lint can be nullified if they refer to a specific
function, which is known to generate diagnostics which are not
interesting. Nullified error messages are not inserted into the source
file, but are written to the standard output. The names of lint func-
tions to ignore are taken from either the file named .errorrc in the
user's home directory, or from the file named by the -I option. If the
file does not exist, no error messages are nullified. If the file does
exist, there must be one function name per line.
Identifies Non-File-Specific Messages
Error messages that cannot be "intuited" are grouped together, and
written to the standard output before any files are touched. These
messages are not inserted into any source file.
Identifies File-Specific Messages
Error message that refer to a specific file, but to no specific line,
are written to the standard output when that file is touched.
Identifies True Errors
Error messages that can be "intuited" are candidates for insertion into
the file to which they refer.
Only true error messages are candidates for inserting into the file to
which they refer. Other error messages are consumed entirely by error or
are written to the standard output. The error program inserts the error
messages into the source file on the line preceding the line the language
processor found in error. Each error message is turned into a one-line com-
ment for the language, and is internally flagged with the string ### at the
beginning of the error, and %%% at the end of the error. This makes pattern
searching for errors easier with an editor, and allows the messages to be
easily removed. In addition, each error message contains the source line
number for the line to which the message refers. A reasonably formatted
source program can be recompiled with the error messages still in it,
without having the error messages themselves cause future errors. For
poorly formatted source programs in free format languages, such as C or
Pascal, it is possible to insert a comment into another comment, which can
wreak havoc with a future compilation. To avoid this, programs with com-
ments and source on the same line should be formatted so that language
statements appear before comments.
The error program catches interrupt and terminate signals, and if in the
insertion phase, will orderly terminate what it is doing.
1. Opens the teletype directly to do user querying.
2. Source files with links make a new copy of the file with only one link
3. Changing a language processor's format of error messages may cause
error to not understand the error message.
4. The error program, since it is purely mechanical, does not filter out
subsequent errors caused by "floodgating" initiated by one syntacti-
cally trivial error. Humans are still much better at discarding these
5. Pascal error messages belong after the lines affected (error puts them
before). The alignment of the \\ marking the point of error is also
disturbed by error.
6. error was designed for work on CRTs at reasonably high speed. It is
less pleasant on slow speed terminals, and has never been used on
Function names to ignore for lint error messages.