Is anybody can correct this irule syntaxe. Thanks

Try this. You had some encoding issues it seems, and were missing a

]

when CLIENTSSL_CLIENTCERT { 
    if {[SSL::cert count] > 0}{ 
        set client_cert [SSL::cert 0] 
        set CLIENT "[join [string trim [string map {"--BEGIN CERTIFICATE--" "" "--END CERTIFICATE--" ""} [X509::whole $client_cert]]] ""]" 
    } else { 
        log local0. "no cert found during clientssl_clientcert" 
    } 
} 
when HTTP_REQUEST { 
    if { [SSL::cert count] > 0 } { 
        set CLIENT "[join [string trim [string map {"--BEGIN CERTIFICATE--" "" "--END CERTIFICATE--" ""} [X509::whole $client_cert]]] ""]" 
        HTTP::header insert "NSClientCert" "—–BEGIN CERTIFICATE—– $CLIENT —–END CERTIFICATE—–" 
    } 
}