On Thu, 28 May 2020 at 17:14, kiran kumar vangara via Gcc-help <gcc-help@xxxxxxxxxxx> wrote: > > Team, > > We have been compiling cpp files with g++ compiler on Redhat Linux OS > machine and as part of this -mt option was given for g++ and it produced > required binary in case # 1 but produced an error in case#2 , I'm sharing > g++ version and the Redhat Linux OS version being used to compile the cpp > code details below .. Can you please let us know what is the meaning of > flag -mt and why it works in case#1 but not in case#2 > > Case#1 > ---------- > g++ (GCC) 4.4.7 20120313 (Red Hat 4.4.7-23) > > Case# 2 > ------------ > g++ (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39) > > In this case the error produced by compiler is > > g++: error: unrecognized command line option -mt > > your help will be greatly appreciated . You are using ancient versions of GCC which have not been supported by the GCC project for many years. You say you are sharing the "Redhat Linux OS version" but you didn't. It looks like you are using Red Hat Enterprise Linux versions 6 and 7, but you didn't say which kind of hardware you're using. The -mt option is an IA-64 option, and I don't think GCC 4.8 supports IA-64. You probably get the error on the second machine because it's different hardware. To find out what -mt means you should look in the manual for the relevant GCC version. If you want support for compilers provided by Red Hat, you should ask Red Hat, and provide more information than you provided here.