文件上次修改时间，精度为毫秒

Question

我有一个目录，里面有一些文件，这些文件是通过脚本修改的，所以它们的mtime只相差几毫秒。file mtime filename命令以秒为单位给出了我最后一次修改的时间，这对我没有什么帮助。我如何才能以毫秒的精度获得他们最后一次更改的时间？

Answer 1

看起来最简单的方法是编写Tcl扩展以获得所需精度的文件修改时间。这其实很简单。

编写代码

#define USE_TCL_STUBS
#include <tcl.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
int precisionmtimeObjCmd (
ClientData cd,
Tcl_Interp* interp,
int objc,
Tcl_Obj * const objv[]
)
{
char        *fn;
int         len1;
struct stat statinfo;
long        value;
/* for UTF-8 locales */
if (objc != 2) {
Tcl_WrongNumArgs(interp, 1, objv, "precisionmtime");
return TCL_ERROR;
}
fn = Tcl_GetStringFromObj(objv[1], &len1);
stat (fn, &statinfo);
value = statinfo.st_mtime;
value *= 1000;
value += statinfo.st_mtim.tv_nsec / 1000000;
Tcl_SetObjResult (interp, Tcl_NewLongObj(value));
return TCL_OK;
}
int Precisionmtime_Init (Tcl_Interp *interp)
{
Tcl_Encoding utf;
if (!Tcl_InitStubs (interp,"8.3",0)) {
return TCL_ERROR;
}
Tcl_CreateObjCommand (interp,"precisionmtime", precisionmtimeObjCmd, NULL, NULL);
Tcl_PkgProvide (interp,"precisionmtime","0.1");
return TCL_OK;
}

编译，链接

bll-tecra:bll$ cc -I/home/bll/local/include -c pmtime.c -o pmtime.o -fPIC
bll-tecra:bll$ cc -L/home/bll/local/lib -o precisionmtime.so -shared pmtime.o -ltclstub8.6

并测试

bll-tecra:bll$ rlwrap tclsh
% load [pwd]/precisionmtime.so
% info commands precision*
precisionmtime
% precisionmtime /home/bll/local/include/tcl.h
1524458623343
% file mtime /home/bll/local/include/tcl.h
1524458623
% 

好吧，为你做了所有的工作。但这很有趣。