void trace(expression)
The most basic action is the trace action, which takes a D expression as its argument and traces the result to the directed buffer. The following statements are examples of trace actions:
trace(execname);
trace(curlwpsinfo->pr_pri);
trace(timestamp / 1000);
trace(`lbolt);
trace("somehow managed to get here");
If the trace action is used to record a buffer, the output format depends on the data that is collected. If dtrace decides that the data looks like an ASCII string, it prints text and the output is terminated by the first null byte. However, if dtrace decides that the data is in a binary form, it prints the output in a hexadecimal format. For example:
0 342 write:entry
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
0: c0 de 09 c2 4a e8 27 54 dc f8 9f f1 9a 20 4b d1 ....J.'T..... K.
10: 9c 7a 7a 85 1b 03 0a fb 3a 81 8a 1b 25 35 b3 9a .zz.....:...%5..
20: f1 7d e6 2b 66 6d 1c 11 f8 eb 40 7f 65 9a 25 f8 .}.+fm....@.e.%.
30: c8 68 87 b2 6f 48 a2 a5 f3 a2 1f 46 ab 3d f9 d2 .h..oH.....F.=..
40: 3d b8 4c c0 41 3c f7 3c cd 18 ad 0d 0d d3 1a 90 =.L.A<.<........
You can force trace to use binary format for ASCII text by using the rawbytes option.