Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mit-eddie!bu-cs!budd
From: budd@bu-cs.BU.EDU (Philip Budne)
Newsgroups: comp.unix.wizards
Subject: Re: pwd
Message-ID: <44969@bu-cs.BU.EDU>
Date: 20 Dec 89 04:57:39 GMT
References: <263@zircon.UUCP>
Reply-To: budd@bu.edu (Phil Budne)
Distribution: comp
Organization: Boston University, Disinformation Technology
Lines: 51

In article <263@zircon.UUCP> davidb@Pacer.UUCP (David Barts) writes:
>
>How does /bin/pwd work?

it stats "." then opendirs ".." and stats each entry until it finds
one with the same device and i number, it then does a chdir("..");
This is repeated until "/" and "." are the same.

buit2% trapfile /bin/pwd
0x2100: stat("/",0xefff594)
0x227c: stat(".",0xefff594)
0x2438: open("..", 0) -> 3
0x2454: fstat(3,0xefff510)
0x2148: chdir("..")
0x2174: fstat(3,0xefff558)
0x23ea: close(3)
0x227c: stat(".",0xefff594)
0x2438: open("..", 0) -> 3
0x2454: fstat(3,0xefff510)
0x2148: chdir("..")
0x2174: fstat(3,0xefff558)
0x2222: stat(".",0xefff558)
0x2222: stat("..",0xefff558)
0x2222: stat("lost+found",0xefff558)
0x2222: stat("dev",0xefff558)
0x2222: stat("etc",0xefff558)
0x2222: stat("bin",0xefff558)
0x2222: stat("mnt",0xefff558)
0x2222: stat("private",0xefff558)
0x2222: stat("pub",0xefff558)
0x2222: stat("tmp",0xefff558)
0x2222: stat("usr",0xefff558)
0x2222: stat(".cshrc",0xefff558)
0x2222: stat(".login",0xefff558)
0x2222: stat(".profile",0xefff558)
0x2222: stat("usr8",0xefff558)
0x2222: stat("stand",0xefff558)
0x2222: stat("vmunix",0xefff558)
0x2222: stat("lib",0xefff558)
0x2222: stat("private.MC68020",0xefff558)
0x2222: stat("usr1",0xefff558)
0x2222: stat("usr2",0xefff558)
0x23ea: close(3)
0x227c: stat(".",0xefff594)
0x22cc: chdir("/usr2/budd")
0x4d3c: ioctl(1,0x40067408,0xefff76c) Inappropriate ioctl for device
0x3c1c: fstat(1,0xefff78c)
0x38d4: close(0)
0x38d4: close(1)
0x38d4: close(2)
/usr2/budd