pro 1 file.txt

proc pro { pattern args} {

   set file [open $args r]
   set lnum 0
   set occ 0
   while {[gets $file line] >=0} {
      incr lnum
      if {[regexp $pattern $line]} {
          incr occ
          puts "The pattern is present in line: $lnum"
          puts "$line"
      } else {
         puts "not found"
      }
   }
   puts "total number of occurencese : $occ"
   close $file
}

proc pro { pattern args} {

   set file [open $args r]
   set lnum 0
   set occ 0
   while {[gets $file line] >=0} {
      incr lnum
      if {[regexp $pattern $line]} {
          incr occ
          puts "The pattern is present in line: $lnum"
          puts "$line"
      } else {
         puts "not found"
      }
   }
   puts "total number of occurencese : $occ"
   close $file
}

proc pro { pattern args} {

   set file [open $args r]
   set lnum 0
   set occ 0
   while {[gets $file line] >=0} {
      incr lnum
      if {[regexp $pattern $line]} {
          incr occ
          puts "The pattern is present in line: $lnum"
          puts "$line"
      } else {
         puts "not found"
      }
   }
   puts "total number of occurencese : $occ"
   close $file
}

regexp "^$lineNo\." $a

if {[regexp "\m$pattern\M" $line]} { ...

if { [string range $line 0 [string length $pattern]] eq "${pattern}." } {
    ...
}