In some cases NoMachine services (nxexec and others) are terminated with signal 13 (SIGPIPE) as soon as nxserver launches them.

Server logs can report, for example:

2016-08-18 16:54:24 877.865 8411 NXSERVER WARNING! Process '/usr/NX/bin/nxexec --auth' with pid '8433/8433' finished with signal 13 after 0,005 seconds.

When a nx processes is finished with signal 13, it may be a symptom of a problem affecting libnss-ldap, a library used for LDAP authentication.

This problem is caused by a write sent to an unconnected socket, which leads to SIGPIPE:

https://bugzilla.redhat.com/show_bug.cgi?id=454315

Possible solutions

Updating RHEL 5 to the last libnss-ldap package. BZ#454315 is solved in nss_ldap-253-25.el5. See the advisory:

http://rhn.redhat.com/errata/RHBA-2010-0260.html

As a workaround, if LDAP authentication is not needed, removing LDAP entries from /etc/nsswitch.conf will makes the NoMachine services to start properly.