Error on git-warning

While I was executing a gui program from the console, I got the following error:

Application initialization failed: couldn't connect to display "0:0"
Error in startup script: invalid command name "mc"
while executing
"mc "git-gui: fatal error""
invoked from within
"if {[catch {package require Tcl 8.4} err]
|| [catch {package require Tk 8.4} err]
} {
catch {wm withdraw .}
tk_messageBox \
-icon error \
-typ..."
(file "/usr/bin/git-gui" line 34)

The problem turn out to be the fact that I am not in the sudoers list.