#LyX 2.0 created this file. For more info see http://www.lyx.org/ \lyxformat 413 \begin_document \begin_header \textclass literate-article \use_default_options false \maintain_unincluded_children false \language english \language_package default \inputencoding default \fontencoding global \font_roman default \font_sans default \font_typewriter default \font_default_family default \use_non_tex_fonts false \font_sc false \font_osf false \font_sf_scale 100 \font_tt_scale 100 \graphics default \default_output_format default \output_sync 0 \bibtex_command default \index_command default \paperfontsize default \spacing single \use_hyperref false \papersize default \use_geometry false \use_amsmath 0 \use_esint 0 \use_mhchem 1 \use_mathdots 1 \cite_engine basic \use_bibtopic false \use_indices false \paperorientation portrait \suppress_date false \use_refstyle 0 \index Index \shortcut idx \color #008000 \end_index \secnumdepth 3 \tocdepth 3 \paragraph_separation indent \paragraph_indentation default \quotes_language english \papercolumns 1 \papersides 1 \paperpagestyle default \tracking_changes false \output_changes false \html_math_output 0 \html_css_as_file 0 \html_be_strict false \end_header \begin_body \begin_layout Title LyX and Literate Programming \begin_inset Newline newline \end_inset An example program \end_layout \begin_layout Author Edmar Wienskoski Jr. \begin_inset Newline newline \end_inset edmar-w-jr@technologist.com \begin_inset Foot status collapsed \begin_layout Plain Layout Modified by Bernard Michael Hurley bernardh@westherts.ac.uk ---- Don't blame Edmar for any errors that have crept in! \end_layout \end_inset \end_layout \begin_layout Abstract \series bold Note: \series default This example program is provided for educational use only. The functionality in this C program has been superceded by the equivalent Python code in \emph on examples/listerrors.lyx \emph default which should be installed in the LyX scripts directory. \end_layout \begin_layout Date \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash today \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset CommandInset toc LatexCommand tableofcontents \end_inset \end_layout \begin_layout Section Introduction \end_layout \begin_layout Standard After typesetting a document, LyX scans the LaTeX log file looking for errors. For each error found, the line number is obtained and a error box is displayed in the LyX screen at that position. \end_layout \begin_layout Standard To use this feature to view compilation errors while working with literate documents, we need a program that filters the compilation errors and puts them in a format suitable for LyX reading it. \end_layout \begin_layout Standard In this document we present a filter that recognizes compilation error messages from noweb, gnu C, and the IBM C compiler (xlc). \end_layout \begin_layout Standard The filter is required to read from standard input, parse for error messages and copy the error messages to the standard output. During the output process, the filter must present the error messages in a format that LyX can interpret, currently, the LaTeX error message format. Of course, nothing will prevent future LyX releases from being able to read other formats as well (like gcc error messages for example). This mechanism is necessary to fully explore the literate programming tool's capabilities. \end_layout \begin_layout Section Algorithm \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap int \end_layout \begin_layout Scrap main (int argc, char **argv) \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap if (argc == 2) { \end_layout \begin_layout Scrap switch (argv[1][0]) { \end_layout \begin_layout Scrap case 'n': \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap break; \end_layout \begin_layout Scrap case 'x': \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap break; \end_layout \begin_layout Scrap case 'a': \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap break; \end_layout \begin_layout Scrap case 's': \end_layout \begin_layout Scrap case 'b': \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap break; \end_layout \begin_layout Scrap case 'g': \end_layout \begin_layout Scrap default: \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap break; \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap } else { \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap @ \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap int main (int argc, char **argv); \end_layout \begin_layout Scrap @ \end_layout \begin_layout Section Data Structures \end_layout \begin_layout Standard We resort to some global variables to allow access from several different routines. These are the buffer and related pointers used during the parse of the input. \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap char buffer[200][200]; \begin_inset Newline newline \end_inset int last_buf_line; \begin_inset Newline newline \end_inset int last_err_line; \begin_inset Newline newline \end_inset int err_line; \begin_inset Newline newline \end_inset @ \end_layout \begin_layout Section The output format \end_layout \begin_layout Standard The output format mimics the TeX error messages format. This function prints a number of lines residing in the global variable \family typewriter buffer \family default , a program name and line number. There is no special requirement on the input strings, they can be anything. \begin_inset Foot status collapsed \begin_layout Plain Layout This function has been slightly changed from EW's original to make scanning a bit easier with LaTeX::scanLogFile(). The test has been added because LyX can crash if empty lines are allowed here --- I can't figure out why! --- BMH \end_layout \end_inset \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap void \end_layout \begin_layout Scrap output_error (int buf_size, int error_line, char *tool) \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap int i; \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap fprintf(stdout, "! Build Error: ==> %s ==> \backslash n", tool); \end_layout \begin_layout Scrap fprintf(stdout, " ... \backslash n \backslash nl.%d ... \backslash n", error_line); \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap for (i=0; i>= \end_layout \begin_layout Scrap void output_error (int buf_size, int error_line, char *tool); \end_layout \begin_layout Scrap @ \end_layout \begin_layout Section Functions Implementation \end_layout \begin_layout Standard Both noweave and notangle routines, always output one single line for each error found, thus to scan the buffer for noweb error messages is enough to exam one input line at a time. Note that the noweb software does not provide a line error number, so all errors boxes related to noweb messages will be displayed at the beginning of the file. \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap last_buf_line = 0; \end_layout \begin_layout Scrap while (fgets(buffer[0], 200, stdin)) { \end_layout \begin_layout Scrap if (noweb_try(0)) \end_layout \begin_layout Scrap output_error(1, err_line, "noweb"); \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap @ \end_layout \begin_layout Standard The examination itself is very inefficient. Unfortunately noweb doesn't have any characteristic that would help to identify one of its error messages. The solution is to collect all possible output messages in an array of strings, and turn the examination process into a linear search in this array. \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap char *noweb_msgs[] = { \end_layout \begin_layout Scrap "couldn't open file", \end_layout \begin_layout Scrap "couldn't open temporary file", \end_layout \begin_layout Scrap "error writing temporary file", \end_layout \begin_layout Scrap "ill-formed option", \end_layout \begin_layout Scrap "unknown option", \end_layout \begin_layout Scrap "Bad format sequence", \end_layout \begin_layout Scrap "Can't open output file", \end_layout \begin_layout Scrap "Can't open temporary file", \end_layout \begin_layout Scrap "Capacity exceeded:", \end_layout \begin_layout Scrap "Ignoring unknown option -", \end_layout \begin_layout Scrap "This can't happen:", \end_layout \begin_layout Scrap "non-numeric line number in" \end_layout \begin_layout Scrap }; \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap char *noweb_msgs_mimic_gcc[] = { \end_layout \begin_layout Scrap ": unescaped << in documentation chunk" \end_layout \begin_layout Scrap }; \end_layout \begin_layout Scrap @ \end_layout \begin_layout Standard A noweb error message can be any string that contains a matching pair of < < \begin_inset space ~ \end_inset \begin_inset space ~ \end_inset \begin_inset space ~ \end_inset > >, or any of the above strings \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap <>= \begin_inset Newline newline \end_inset int \begin_inset Newline newline \end_inset noweb_try (int buf_line) \begin_inset Newline newline \end_inset { \begin_inset Newline newline \end_inset char *s, *t, *b; \begin_inset Newline newline \end_inset int i; \begin_inset Newline newline \end_inset \begin_inset Newline newline \end_inset b = buffer[buf_line]; \begin_inset Newline newline \end_inset err_line = 0; \begin_inset Newline newline \end_inset \begin_inset Newline newline \end_inset for (i=0; i<1; i++) { \begin_inset Newline newline \end_inset s = (char *)strstr (b, noweb_msgs_mimic_gcc[i]); \begin_inset Newline newline \end_inset if (s != NULL) { \begin_inset Newline newline \end_inset t = (char *)strchr(buffer[buf_line], ':'); \begin_inset Newline newline \end_inset err_line = atoi(t+1); \begin_inset Newline newline \end_inset t = buffer[buf_line]; \begin_inset Newline newline \end_inset ++s; \begin_inset Newline newline \end_inset while (*(t++) = *(s++)); \begin_inset Newline newline \end_inset return 1; \begin_inset Newline newline \end_inset } \begin_inset Newline newline \end_inset } \begin_inset Newline newline \end_inset s = (char *)strstr(b, "<<"); \begin_inset Newline newline \end_inset if (s != NULL) { \begin_inset Newline newline \end_inset s = (char *)strstr(s+2, ">>"); \begin_inset Newline newline \end_inset if (s != NULL) { \begin_inset Newline newline \end_inset return 1; \begin_inset Newline newline \end_inset } \begin_inset Newline newline \end_inset } else { \begin_inset Newline newline \end_inset for (i = 0; i < 12; ++i) { \begin_inset Newline newline \end_inset s = (char *)strstr (b, noweb_msgs[i]); \begin_inset Newline newline \end_inset if (s != NULL) { \begin_inset Newline newline \end_inset return 1; \begin_inset Newline newline \end_inset } \begin_inset Newline newline \end_inset } \begin_inset Newline newline \end_inset } \begin_inset Newline newline \end_inset return 0; \begin_inset Newline newline \end_inset } \begin_inset Newline newline \end_inset @ \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap int noweb_try (int buf_line); \end_layout \begin_layout Scrap @ \end_layout \begin_layout Standard The xlc compiler always outputs one single line for each error found, thus to scan the buffer for xlc error messages it is enough to exam one input line at a time. \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap last_buf_line = 0; \end_layout \begin_layout Scrap while (fgets(buffer[last_buf_line], 200, stdin)) { \end_layout \begin_layout Scrap if (xlc_try(0)) \end_layout \begin_layout Scrap output_error(1, err_line, "xlc"); \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap @ \end_layout \begin_layout Standard A xlc error message is easy to identify. Every error message starts with a quoted string with no spaces, a comma, a space, the word \begin_inset Quotes eld \end_inset line \begin_inset Quotes erd \end_inset , a space, and some variable text. The following routine tests if a given buffer line matches this criteria: \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap int \end_layout \begin_layout Scrap xlc_try (int buf_line) \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap char *s, *t; \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap t = buffer[buf_line]; \end_layout \begin_layout Scrap s = t+1; \end_layout \begin_layout Scrap while (*s != '"' && *s != ' ' && *s != ' \backslash 0') \end_layout \begin_layout Scrap s++; \end_layout \begin_layout Scrap if (*t != '"' || *s != '"' || strncmp(s+1, ", line ", 7) != 0) \end_layout \begin_layout Scrap return 0; \end_layout \begin_layout Scrap s += 8; \end_layout \begin_layout Scrap err_line = atoi(s); \end_layout \begin_layout Scrap return 1; \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap @ \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap int xlc_try (int buf_line); \end_layout \begin_layout Scrap @ \end_layout \begin_layout Standard The gcc compiler error messages are more complicated to scan. Each error can span more than one line in the buffer. The good news is that every buffer line on each error has the same pattern, and share the same line number. Thus the strategy will be to accumulate lines in the buffer while the reported line number is still the same. At the time they differ, all the accumulated lines, except the last one, will belong to one single error message, which now can be output-ed to LyX. \end_layout \begin_layout Standard Every gcc error message contains a string with no space followed by a \begin_inset Quotes eld \end_inset : \begin_inset Quotes eld \end_inset . If the next character is a space, then this line is a header of a error message and the next line will detail the line number of the source code where the error was found. Otherwise, the next thing is a integer number followed by another \begin_inset Quotes eld \end_inset : \begin_inset Quotes eld \end_inset . \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap char *s, *t; \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap last_buf_line = 0; \end_layout \begin_layout Scrap while (fgets(buffer[last_buf_line], 200, stdin)) { \end_layout \begin_layout Scrap /****** Skip lines until I find an error */ \end_layout \begin_layout Scrap s = (char *)strpbrk(buffer[last_buf_line], " :"); \end_layout \begin_layout Scrap if (s == NULL || *s == ' ') \end_layout \begin_layout Scrap continue; /* No gcc error found here */ \end_layout \begin_layout Scrap do { \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap /****** OK It is an error message, get line number */ \end_layout \begin_layout Scrap err_line = atoi(s+1); \end_layout \begin_layout Scrap if (last_err_line == 0 || last_err_line == err_line) { \end_layout \begin_layout Scrap last_err_line = err_line; \end_layout \begin_layout Scrap continue; /* It's either a header or a continuation, don't output yet */ \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap /****** Completed the scan of one error message, output it to LyX */ \end_layout \begin_layout Scrap discharge_buffer(1); \end_layout \begin_layout Scrap break; \end_layout \begin_layout Scrap } while (fgets(buffer[last_buf_line], 200, stdin)); \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap /****** EOF completes the scan of whatever was being scanned */ \end_layout \begin_layout Scrap discharge_buffer(0); \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap @ \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap /****** Search first ":" in the error number */ \end_layout \begin_layout Scrap s = (char *)strpbrk(buffer[last_buf_line], " :"); \end_layout \begin_layout Scrap last_buf_line++; \end_layout \begin_layout Scrap if (s == NULL || *s == ' ') \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap /****** Search second ":" in the error number */ \end_layout \begin_layout Scrap t = (char *)strpbrk(s+1, " :"); \begin_inset Newline newline \end_inset if (t == NULL || *t == ' ') \begin_inset Newline newline \end_inset <> \begin_inset Newline newline \end_inset /****** Verify if is all digits between ":" */ \begin_inset Newline newline \end_inset if (t != s+1+strspn(s+1, "0123456789")) \begin_inset Newline newline \end_inset <> \begin_inset Newline newline \end_inset @ \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap err_line = 0; \end_layout \begin_layout Scrap discharge_buffer(1); \end_layout \begin_layout Scrap continue; \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap @ \end_layout \begin_layout Standard As we mentioned, when the scan of one gcc error message is completed everything in the buffer except the last line is one single error message. But if the scan terminates with a EOF or through finding one line that does not match the gcc error message criteria, then there is no \begin_inset Quotes eld \end_inset last line \begin_inset Quotes erd \end_inset in the buffer to be concerned with. In those cases we empty the buffer completely. \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap void \end_layout \begin_layout Scrap discharge_buffer (int save_last) \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap if (last_err_line != 0) { \end_layout \begin_layout Scrap clean_gcc_messages(); \end_layout \begin_layout Scrap if (save_last != 0) { \end_layout \begin_layout Scrap output_error(last_buf_line-1, last_err_line, "gcc"); \end_layout \begin_layout Scrap strcpy (buffer[0], buffer[last_buf_line-1]); \end_layout \begin_layout Scrap last_err_line = err_line; \end_layout \begin_layout Scrap last_buf_line = 1; \end_layout \begin_layout Scrap } else { \end_layout \begin_layout Scrap ++last_buf_line; \end_layout \begin_layout Scrap clean_gcc_messages(); \end_layout \begin_layout Scrap output_error(last_buf_line-1, last_err_line, "gcc"); \end_layout \begin_layout Scrap last_err_line = 0; \end_layout \begin_layout Scrap last_buf_line = 0; \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap @ \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap void discharge_buffer (int save_last); \end_layout \begin_layout Scrap @ \end_layout \begin_layout Standard The next function \begin_inset Quotes eld \end_inset cleans \begin_inset Quotes erd \end_inset superfluous information from gcc messages, namely the name of the noweb file and the line number of the Error. \begin_inset Foot status collapsed \begin_layout Plain Layout More could be done. For instance, some way of distinguishing between gcc Errors and Warnings should be devised. \end_layout \end_inset \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap void \end_layout \begin_layout Scrap clean_gcc_messages () \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap int index; \end_layout \begin_layout Scrap char search [30]; \end_layout \begin_layout Scrap char *tail, *head; \end_layout \begin_layout Scrap int search_len = sprintf(search, ".nw:%d:", last_err_line); \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap for (index = 0; index < last_buf_line-1; index++) { \end_layout \begin_layout Scrap tail = (char *)strstr (buffer[index], search); \end_layout \begin_layout Scrap if ( tail == NULL) { \end_layout \begin_layout Scrap tail = (char *) strstr (buffer[index], ".nw:"); \end_layout \begin_layout Scrap if (tail) { \end_layout \begin_layout Scrap tail += 4; \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap } else { \end_layout \begin_layout Scrap tail += search_len; \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap if (tail != NULL) { \end_layout \begin_layout Scrap head = buffer[index]; \end_layout \begin_layout Scrap while (*(head++) = *(tail++)); \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap @ \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap void clean_gcc_messages (); \end_layout \begin_layout Scrap @ \end_layout \begin_layout Standard To combine the scan of noweb error messages and xlc error messages is very simple. We just try each one for every input line: \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap last_buf_line = 0; \begin_inset Newline newline \end_inset while (fgets(buffer[0], 200, stdin)) { \begin_inset Newline newline \end_inset if (noweb_try(0)) \begin_inset Newline newline \end_inset output_error(1, err_line, "noweb"); \begin_inset Newline newline \end_inset else if (xlc_try(0)) \begin_inset Newline newline \end_inset output_error(1, err_line, "xlc"); \begin_inset Newline newline \end_inset } \begin_inset Newline newline \end_inset } \begin_inset Newline newline \end_inset @ \end_layout \begin_layout Standard To combine the scan of noweb error messages and gcc error messages is simple if we realize that it is not possible to find a noweb error message in the middle of a gcc error message. So we just repeat the gcc procedure and test for noweb error messages in the beginning of the scan: \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap { \end_layout \begin_layout Scrap char *s, *t; \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap last_buf_line = 0; \end_layout \begin_layout Scrap while (fgets(buffer[last_buf_line], 200, stdin)) { \end_layout \begin_layout Scrap /****** Skip lines until I find an error */ \end_layout \begin_layout Scrap if (last_buf_line == 0 && noweb_try(0)) { \end_layout \begin_layout Scrap output_error(1, err_line, "noweb"); \end_layout \begin_layout Scrap continue; \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap s = (char *)strpbrk(buffer[last_buf_line], " :"); \end_layout \begin_layout Scrap if (s == NULL || *s == ' ') \end_layout \begin_layout Scrap continue; /* No gcc error found here */ \end_layout \begin_layout Scrap do { \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap /****** OK It is an error, get line number */ \end_layout \begin_layout Scrap err_line = atoi(s+1); \end_layout \begin_layout Scrap if (last_err_line == 0 || last_err_line == err_line) { \end_layout \begin_layout Scrap last_err_line = err_line; \end_layout \begin_layout Scrap continue; /* It's either a header or a continuation, don't output yet */ \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap /****** Completed the scan of one error message, output it to LyX */ \end_layout \begin_layout Scrap discharge_buffer(1); \end_layout \begin_layout Scrap break; \end_layout \begin_layout Scrap } while (fgets(buffer[last_buf_line], 200, stdin)); \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap /****** EOF completes the scan of whatever was being scanned */ \end_layout \begin_layout Scrap discharge_buffer(0); \end_layout \begin_layout Scrap } \end_layout \begin_layout Scrap @ \end_layout \begin_layout Section Wrapping the code into a file \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap #include \end_layout \begin_layout Scrap #include \end_layout \begin_layout Scrap \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap <> \end_layout \begin_layout Scrap @ \end_layout \begin_layout Standard To build this program, we want to add the \begin_inset Quotes eld \end_inset -L \begin_inset Quotes erd \end_inset option in the tangle command to force gdb to load the file \family typewriter Literate.nw \family default instead of \family typewriter listerrors.c \family default . In accordance with this, we pass the \begin_inset Quotes eld \end_inset -g \begin_inset Quotes erd \end_inset option to gcc. \end_layout \begin_layout Scrap <>= \end_layout \begin_layout Scrap #!/bin/sh \end_layout \begin_layout Scrap if [ -z "$NOWEB_SOURCE" ]; then NOWEB_SOURCE=Literate.nw; fi \end_layout \begin_layout Scrap if [ -z "$NOWEB_OUTPUT_DIR" ]; then NOWEB_OUTPUT_DIR=.; fi \end_layout \begin_layout Scrap notangle -L -Rlisterrors.c ${NOWEB_SOURCE} > ${NOWEB_OUTPUT_DIR}/listerrors.c \end_layout \begin_layout Scrap gcc -g -o listerrors listerrors.c \end_layout \begin_layout Scrap @ \end_layout \begin_layout Standard This project can be tangled and compiled from LyX if you set \family typewriter \backslash build_command \family default to call a generic script that always extracts a scrap named \family typewriter build-script \family default and executes it. Here is a example of such generic script: \end_layout \begin_layout LyX-Code #!/bin/sh \begin_inset Newline newline \end_inset notangle -Rbuild-script $1 | env NOWEB_SOURCE=$1 NOWEB_OUTPUT_DIR=$r sh \end_layout \begin_layout LyX-Code \end_layout \end_body \end_document