Безопасно ли «выключение -r сейчас»? [дубликат]

Используйте для этого sed , как показано ниже:

SHW@SHW:/tmp $ cat a
this is line one
and this is line two
the third and the
fourth must be pasted too

SHW@SHW:/tmp $ sed 'N;s/\n/ /' a -i

SHW@SHW:/tmp $ cat a
this is line one and this is line two
the third and the fourth must be pasted too