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Использование в приложениях (Application usage)
Because of the extremely terse nature of the default error
messages, the prudent script writer begins the ed input commands
with an H command, so that if any errors do occur at least some
clue as to the cause is made available.
In earlier versions of this standard, an obsolescent - option was
described. This is no longer specified. Applications should use
the -s option. Using - as a file operand now produces unspecified
results. This allows implementations to continue to support the
former required behavior.
