zabbix_agent fails to start, it exits with no error message nor a return code > 0. This the full output of strace zabbix_agent:

execve("/usr/sbin/zabbix_agent", ["zabbix_agent"], [/* 55 vars */]) = 0
brk(0) = 0x168c000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f768b6ee000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY) = 3
fstat(3,

{st_mode=S_IFREG|0644, st_size=131930, ...}

) = 0
mmap(NULL, 131930, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f768b6cd000
close(3) = 0
open("/lib/libm.so.6", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P>\0\0\0\0\0\0@"..., 832) = 832
fstat(3,

{st_mode=S_IFREG|0755, st_size=581178, ...}

) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f768b6cc000
mmap(NULL, 2625752, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f768b251000
mprotect(0x7f768b2d2000, 2093056, PROT_NONE) = 0
mmap(0x7f768b4d1000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x80000) = 0x7f768b4d1000
close(3) = 0
open("/lib/libresolv.so.2", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\2408\0\0\0\0\0\0@"..., 832) = 832
fstat(3,

{st_mode=S_IFREG|0755, st_size=94083, ...}

) = 0
mmap(NULL, 2185864, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f768b03b000
mprotect(0x7f768b04e000, 2093056, PROT_NONE) = 0
mmap(0x7f768b24d000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x12000) = 0x7f768b24d000
mmap(0x7f768b24f000, 6792, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f768b24f000
close(3) = 0
open("/lib/libc.so.6", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0\353\1\0\0\0\0\0@"..., 832) = 832
fstat(3,

{st_mode=S_IFREG|0755, st_size=1635841, ...}

) = 0
mmap(NULL, 3483656, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f768ace8000
mprotect(0x7f768ae31000, 2097152, PROT_NONE) = 0
mmap(0x7f768b031000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x149000) = 0x7f768b031000
mmap(0x7f768b036000, 18440, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f768b036000
close(3) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f768b6cb000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f768b6ca000
arch_prctl(ARCH_SET_FS, 0x7f768b6ca6f0) = 0
mprotect(0x7f768b031000, 16384, PROT_READ) = 0
mprotect(0x7f768b24d000, 4096, PROT_READ) = 0
mprotect(0x7f768b4d1000, 4096, PROT_READ) = 0
mprotect(0x7f768b6ef000, 4096, PROT_READ) = 0
munmap(0x7f768b6cd000, 131930) = 0
brk(0) = 0x168c000
brk(0x16ad000) = 0x16ad000
open("/etc/zabbix/zabbix_agent.conf", O_RDONLY) = 3
fstat(3,

{st_mode=S_IFREG|0640, st_size=1378, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f768b6ed000
read(3, "# This is a config file for zabbi"..., 4096) = 1378
read(3, ""..., 4096) = 0
close(3) = 0
munmap(0x7f768b6ed000, 4096) = 0
syscall_293(0x7fffa62ffcf0, 0x80000, 0x41b4c9, 0x100, 0x7f768b6ca6f0, 0x1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) = 0
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f768b6ca7c0) = 24254
close(4) = 0
fcntl(3, F_SETFD, 0) = 0
fstat(3, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f768b6ed000
read(3, "webmind-ws1.cb-it.local\n"..., 4096) = 24
read(3, ""..., 4096) = 0
read(3, ""..., 4096) = 0
close(3) = 0
wait4(24254, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 24254
— SIGCHLD (Child exited) @ 0 (0) —
munmap(0x7f768b6ed000, 4096) = 0
open("/etc/zabbix/zabbix_agent.conf", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0640, st_size=1378, ...}

) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f768b6ed000
read(3, "# This is a config file for zabbi"..., 4096) = 1378
read(3, ""..., 4096) = 0
close(3) = 0
munmap(0x7f768b6ed000, 4096) = 0
rt_sigaction(SIGINT,

{0x4035f0, [INT], SA_RESTORER|SA_RESTART, 0x7f768ad19f90}

,

{SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTERM, {0x4035f0, [TERM], SA_RESTORER|SA_RESTART, 0x7f768ad19f90}, {SIG_DFL, [], 0}

, 8) = 0
rt_sigaction(SIGQUIT,

{0x4035f0, [QUIT], SA_RESTORER|SA_RESTART, 0x7f768ad19f90}

,

{SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGALRM, {0x4035f0, [ALRM], SA_RESTORER|SA_RESTART, 0x7f768ad19f90}, {SIG_DFL, [], 0}

, 8) = 0
alarm(3) = 0
getpeername(0, 0x7fffa6302190, [16]) = -1 ENOTSOCK (Socket operation on non-socket)
alarm(0) = 3
exit_group(0) = ?