$ sudo -H strace vserver blah enter
...
execve("/usr/sbin/vnamespace", ["/usr/sbin/vnamespace", "--enter", "/etc/vservers/blah", "--", "/usr/sbin/vserver", "----nonamespace", "kissouraces", "enter"], [/* 18 vars */]) = 0
stat64("/etc/vservers/blah/vdir", {st_mode=S_IFDIR|0755, st_size=480, ...}) = 0
access("/etc/vservers/blah/legacy", F_OK) = -1 ENOENT (No such file or directory)
open("/etc/vservers/blah/run", O_RDONLY|O_LARGEFILE) = 3
_llseek(3, 0, [6], SEEK_END)            = 0
_llseek(3, 0, [0], SEEK_SET)            = 0
read(3, "49156\n", 7)                   = 6
close(3)                                = 0
vserver(0, 0x3f, 0, 0xbfb93df3, 0xc004) = 131074
vserver(0x2e050000, 0xc004, 0xbfb91f30, 0xbfb93df3, 0xc004) = 0
vserver(0, 0x3f, 0, 0xbfb91fcc, 0xc004) = 131074
vserver(0x2020000, 0xc004, 0xbfb91e44, 0xbfb91fcc, 0xbfb91eb0) = 0
old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7ffc000
stat64("/etc/vservers/blah", {st_mode=S_IFDIR|0755, st_size=272, ...}) = 0
stat64("/etc/vservers/old.blah", {st_mode=S_IFDIR|0755, st_size=272, ...}) = 0
open("/etc/vservers/blah/context", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
write(2, "vnamespace: ", 12vnamespace: )            = 12
write(2, "vc_xidopt2xid(\"/etc/vservers/kis"..., 42vc_xidopt2xid("/etc/vservers/blah")) = 42
write(2, ": ", 2: )                       = 2
write(2, "No such file or directory", 25No such file or directory) = 25
write(2, "\n", 1
)                       = 1
_exit(255)                              = ?