MKSTR(1) FreeBSD General Commands Manual MKSTR(1)


mkstrcreate an error message file by massaging C source


mkstr [ -] mesgfile prefix file ...


The mkstr utility creates a file containing error messages extracted from C source, and restructures the same C source, to utilize the created error message file. The intent of mkstr was to reduce the size of large programs and reduce swapping (see BUGS section below).

The mkstr utility processes each of the specified files, placing a restructured version of the input in a file whose name consists of the specified prefix and the original name. A typical usage of mkstr is

mkstr pistrings xx *.c

This command causes all the error messages from the C source files in the current directory to be placed in the file pistrings and restructured copies of the sources to be placed in files whose names are prefixed with “ xx”.


Error messages are placed at the end of the specified message file for recompiling part of a large mkstred program.

The mkstr utility finds error messages in the source by searching for the string ‘ error("’ in the input stream. Each time it occurs, the C string starting at the ‘ "’ is stored in the message file followed by a null character and a new-line character; The new source is restructured with lseek(2) pointers into the error message file for retrieval.

char efilname = "/usr/lib/pi_strings"; 
int efil = -1; 
error(a1, a2, a3, a4) 
 char buf[256]; 
 if (efil < 0) { 
  efil = open(efilname, 0); 
  if (efil < 0) 
   err(1, "%s", efilname); 
 if (lseek(efil, (off_t)a1, SEEK_SET) < 0 || 
     read(efil, buf, 256) <= 0) 
  err(1, "%s", efilname); 
 printf(buf, a2, a3, a4); 


An mkstr utility appeared in 3.0BSD.


The mkstr utility was intended for the limited architecture of the PDP 11 family. Very few programs actually use it. The memory savings are negligible in modern computers.
November 1, 2002 FreeBSD