Awk or sed, move first column to end

To get the first columns in each line using awk you can do the following:

< testfile awk '{print $1}'
aaa
aaa
aaa
www
hhh
hhh

These are your keys for the rest of the lines. So you may create a hash table, using the first column as a key and the second column of the line as the value:

< testfile awk '{table[$1]=table[$1] $2;} END {for (key in table) print key " => " table[key];}'
www => yyy
aaa => bbbNULLbbb
hhh => 111111

To get the whole rest of the line, starting with column 2, you need to collect all columns:

< testfile awk '{line="";for (i = 2; i <= NF; i++) line = line $i " "; table[$1]=table[$1] line;} END {for (key in table) print key " => " table[key];}'
www => yyy hhh NULL NULL NULL NULL 
aaa => bbb ccc ddd NULL NULL NULL NULL NULL NULL NULL NULL NULL bbb ccc    NULL NULL NULL NULL 
hhh => 111 333 yyy ooo hyy uuuioooy 111 333 yyy ooo hyy NULL 

Using awk, by acting upon number of fields

$ awk 'NF==1{print p "\t" $1; next} {p=$1} 1' ip.txt
john    math
john    science
paul    math
paul    science
rosy    math
jill    science
rob     math
rob     science
hary    math

• {p=$1} 1 for lines other than single field, save first column and print the line
• NF==1{print p "\t" $1; next} if only one field is present, print previous field, tab and the field from input line. next will skip rest of statements and process next line

if tab separation doesn't work out, use column

$ awk 'NF==1{print p,$1; next} {p=$1} 1' ip.txt | column -t
john  math
john  science
paul  math
paul  science
rosy  math
jill  science
rob   math
rob   science
hary  math