echo ": whos ..." 1>&2
exit 1
fi
for i
do

gawk -F: '{print $1, $5}' /etc/passwd |
grep -i "$i"
done

    whos     
chas      :

$ whos chas "Marilou Smith"

chas  
msmith  

 whos        for.
      "$8"   for  -
,       for  ,  ,  
.          ,  -
        .   -
 "$@"  for     
  ,        .

      whos   -
   /etc/passwd.   for  gawk    
/etc/passwd  ($1)   ($5)  ( , , 
     ). $1  $5   , -
    gawk;       -
  . (     , -
   .)       
 grep.  grep        $i (-
    ).  -i  grep  -
          ,  $i.

    gawk    , -
     (|).  NEWLINE,  -
    (    ,  
  ),   ,   NEWLINE   
 .   ,   who |   
RETURN.    .     sort 
   RETURN,     who.

     NEWLINE,    .

  whos      /etc/passwd, -
       ,  -
     /etc/passwd.     /etc/passwd
     "   "  12. .
 man-  gawk  grep.

 28.   Bourne Again Shell 881