редактор потока (stream editor)
Использование в приложениях (Application usage)
Regular expressions match entire strings, not just individual
lines, but a <newline> is matched by '\n' in a sed RE; a
<newline> is not allowed by the general definition of regular
expression in POSIX.1‐2008. Also note that '\n' cannot be used to
match a <newline> at the end of an arbitrary input line;
<newline> characters appear in the pattern space as a result of
the N editing command.
When using sed to process pathnames, it is recommended that
LC_ALL, or at least LC_CTYPE and LC_COLLATE, are set to POSIX or
C in the environment, since pathnames can contain byte sequences
that do not form valid characters in some locales, in which case
the utility's behavior would be undefined. In the POSIX locale
each byte is a valid single-byte character, and therefore this
problem is avoided.
