Como posso exibir as primeiras n linhas diferentes em dois arquivos de um shell?

Question

Como posso exibir as primeiras n linhas diferentes em dois arquivos de um shell? Eu tentei com grep -vfmas realmente não funciona.

Suponha que n = 5 Esta entrada:

file1

a
b
c
d
e
f
g
h
i
j
k
l
m
n
o

file2

This line is not the same
b
c
d
This is still not the same
Neither is this
g
h
Nor this
DIFFERENT
k
This is not the same, too
m
another different line
o

Produziria a saída:

This line is not the same
This is still not the same
Neither is this
Nor this
DIFFERENT

Answer 1

Esta é a minha proposta:

diff -u file1 file2 --unchanged-line-format= --old-line-format= --new-line-format=%L | head -n 5

This line is not the same
This is still not the same
Neither is this
Nor this
DIFFERENT

Answer 2

Supondo que seus arquivos não contenham o caractere TAB (se contiverem, escolha outro delimitador inequívoco), você poderia fazer

$ paste file1 file2 | awk -F'\t' '$2 != $1 {print $2; n++} n==5 {exit}'
This line is not the same
This is still not the same
Neither is this
Nor this
DIFFERENT

Answer 3

Usando primitivos bash, usando descritores de arquivos fixos para manter as coisas simples. (Não testado)

# open the two files on fd8 and fd9, should have some error checking
exec 8<file1 9<file2
# start the loop
for(c=0;c<6;)
do
    # read a line from first file, don't worry about EOF 
    IFS="" read -r -u 8 l1
    # read a line from second file, exit the loop if EOF
    read -r -u 9 l2 || break
    # loop if the 2 lines are the same
    [ "$l1" -eq "$l2" ] && continue
    # ok, a different line. Output from file2, bump count and loop
    let c++
    printf '%s\n' "$l2"
done
# If we get here we either have hit EOF on file2 or have printed our 6 lines
# Either way just tidy up
# close the file descriptiors
exec 8<&- 9<&-