滲透測試、系統審計或應急響應時，需快速定位密碼檔。以下彙整主流 Unix/Linux 系統的密碼檔預設路徑：
| 作業系統 | 密碼檔路徑 | 備註 |
|---|---|---|
| AIX 3 | /etc/security/passwd | 或 /tcb/auth/files// |
| A/UX 3.0s | /tcb/files/auth/?/* | |
| BSD 4.3-Reno | /etc/master.passwd | |
| ConvexOS 10 | /etc/shadpw | |
| ConvexOS 11 | /etc/shadow | |
| DG/UX | /etc/tcb/aa/user/ | |
| EP/IX | /etc/shadow | |
| HP-UX | /.secure/etc/passwd | |
| IRIX 5 | /etc/shadow | |
| Linux 1.1+ | /etc/shadow | 現代通用 |
| OSF/1 | /etc/passwd[.dir .pag] | |
| SCO Unix 3.2.x | /tcb/auth/files// | |
| SunOS 4.1 (C2) | /etc/security/passwd.adjunct | ##username |
| SunOS 5.0 (Solaris) | /etc/shadow | |
| System V Release 4.0 | /etc/shadow | |
| System V Release 4.2 | /etc/security/* database | |
| Ultrix 4 | /etc/auth[.dir .pag] | |
| UNICOS | /etc/udb |
/etc/shadow 儲存雜湊密碼，/etc/passwd 僅存公開帳戶資訊。