Show file descriptor related information

-y option can be used to print file path associated with each file descriptor. Compare the following outputs:

a) Without -y option:

# strace ls
......
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=98309, ...}) = 0
......

b) With -y option:

# strace -y ls
......
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3</etc/ld.so.cache>
fstat(3</etc/ld.so.cache>, {st_mode=S_IFREG|0644, st_size=98309, ...}) = 0
......

Furthermore, -yy option can be used to print protocol specific information associated with socket file descriptors, and block/character device number associated with device file descriptors. Compare following outputs:

a) Without -yy option:

# strace ip
......
socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_ROUTE) = 3
setsockopt(3, SOL_SOCKET, SO_SNDBUF, [32768], 4) = 0
......

# strace ls
......
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(0x88, 0x1), ...}) = 0
......

b) With -yy option:

# strace -yy ip
......
socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_ROUTE) = 3<NETLINK:[29833]>
setsockopt(3<NETLINK:[29833]>, SOL_SOCKET, SO_SNDBUF, [32768], 4) = 0
......

# strace -yy ls
......
fstat(1</dev/pts/1<char 136:1>>, {st_mode=S_IFCHR|0620, st_rdev=makedev(0x88, 0x1), ...}) = 0
......