1.\" Copyright (c) 1980, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)xstr.1 8.2 (Berkeley) 12/30/93 7.\" 8.Dd 9.Dt XSTR 1 10.Os BSD 3 11.Sh NAME 12.Nm xstr 13.Nd "extract strings from C programs to implement shared strings" 14.Sh SYNOPSIS 15.Nm xstr 16.Op Fl c 17.Op Fl 18.Op Ar file 19.Sh DESCRIPTION 20.Nm Xstr 21maintains a file 22.Pa strings 23into which strings in component parts of a large program are hashed. 24These strings are replaced with references to this common area. 25This serves to implement shared constant strings, most useful if they 26are also read-only. 27.Pp 28Available options: 29.Bl -tag -width Ds 30.It Fl 31.Nm Xstr 32reads from the standard input. 33.It Fl c 34.Nm Xstr 35will extract the strings from the C source 36.Ar file 37or the standard input 38.Pq Fl , 39replacing 40string references by expressions of the form (&xstr[number]) 41for some number. 42An appropriate declaration of 43.Nm xstr 44is prepended to the file. 45The resulting C text is placed in the file 46.Pa x.c , 47to then be compiled. 48The strings from this file are placed in the 49.Pa strings 50data base if they are not there already. 51Repeated strings and strings which are suffixes of existing strings 52do not cause changes to the data base. 53.El 54.Pp 55After all components of a large program have been compiled a file 56.Pa xs.c 57declaring the common 58.Nm xstr 59space can be created by a command of the form 60.Bd -literal -offset indent 61xstr 62.Ed 63.Pp 64The file 65.Pa xs.c 66should then be compiled and loaded with the rest 67of the program. 68If possible, the array can be made read-only (shared) saving 69space and swap overhead. 70.Pp 71.Nm Xstr 72can also be used on a single file. 73A command 74.Bd -literal -offset indent 75xstr name 76.Ed 77.Pp 78creates files 79.Pa x.c 80and 81.Pa xs.c 82as before, without using or affecting any 83.Pa strings 84file in the same directory. 85.Pp 86It may be useful to run 87.Nm xstr 88after the C preprocessor if any macro definitions yield strings 89or if there is conditional code which contains strings 90which may not, in fact, be needed. 91An appropriate command sequence for running 92.Nm xstr 93after the C preprocessor is: 94.Pp 95.Bd -literal -offset indent -compact 96cc \-E name.c | xstr \-c \- 97cc \-c x.c 98mv x.o name.o 99.Ed 100.Pp 101.Nm Xstr 102does not touch the file 103.Pa strings 104unless new items are added, thus 105.Xr make 1 106can avoid remaking 107.Pa xs.o 108unless truly necessary. 109.Sh FILES 110.Bl -tag -width /tmp/xsxx* -compact 111.It Pa strings 112Data base of strings 113.It Pa x.c 114Massaged C source 115.It Pa xs.c 116C source for definition of array `xstr' 117.It Pa /tmp/xs* 118Temp file when `xstr name' doesn't touch 119.Pa strings 120.El 121.Sh SEE ALSO 122.Xr mkstr 1 123.Sh BUGS 124If a string is a suffix of another string in the data base, 125but the shorter string is seen first by 126.Nm xstr 127both strings will be placed in the data base, when just 128placing the longer one there will do. 129.Sh HISTORY 130The 131.Nm 132command appeared in 133.Bx 3.0 . 134