//==========================================================//
saurabh@saurabh-Dell-System-XPS-L502X:/usr/local/freesurfer$ cd $SUBJECTS_DIR
saurabh@saurabh-Dell-System-XPS-L502X:~/Desktop/saurabh_freesurfer$

saurabh@saurabh-Dell-System-XPS-L502X:/usr/local/freesurfer$ cat `which tkmedit`
#!/bin/tcsh -ef
source $FREESURFER_HOME/bin/tcl_setup
exec $FREESURFER_HOME/tktools/tkmedit.bin $argv
saurabh@saurabh-Dell-System-XPS-L502X:/usr/local/freesurfer$


saurabh@saurabh-Dell-System-XPS-L502X:/usr/local/freesurfer$ tkmedit subject1 rawavg.mgz
/usr/local/freesurfer/tktools/tkmedit.bin: Command not found.
saurabh@saurabh-Dell-System-XPS-L502X:/usr/local/freesurfer$
//===============================================================//

Still error is present...?