reinout@reinout:~> strace ionice -c3
execve("/usr/bin/ionice", ["ionice", "-c3"], [/* 95 vars */]) = 0
brk(0)                                  = 0x804b000
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f4f000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=119958, ...}) = 0
mmap2(NULL, 119958, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7f31000
close(3)                                = 0
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\340`\1"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=1491141, ...}) = 0
mmap2(NULL, 1234372, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7e03000
fadvise64(3, 0, 1234372, POSIX_FADV_WILLNEED) = 0
mmap2(0xb7f2b000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x128) = 0xb7f2b000
mmap2(0xb7f2e000, 9668, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb7f2e000
close(3)                                = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7e02000
set_thread_area({entry_number:-1 -> 6, base_addr:0xb7e026c0, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
mprotect(0xb7f2b000, 4096, PROT_READ)   = 0
munmap(0xb7f31000, 119958)              = 0
ioprio_set(0x1, 0, 0x6007)              = -1 EPERM (Operation not permitted)
dup(2)                                  = 3
fcntl64(3, F_GETFL)                     = 0x2 (flags O_RDWR)
brk(0)                                  = 0x804b000
brk(0x806c000)                          = 0x806c000
fstat64(3, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 3), ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f4e000
_llseek(3, 0, 0xbfe14ef8, SEEK_CUR)     = -1 ESPIPE (Illegal seek)
write(3, "ioprio_set: Operation not permit"..., 36ioprio_set: Operation not permitted
) = 36
close(3)                                = 0
munmap(0xb7f4e000, 4096)                = 0
exit_group(0)                           = ?
Process 14988 detached