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echo

- echo arguments to standard output

用法概要

/usr/ucb/echo [-n] [argument]

描述

echo writes its arguments, separated by BLANKs and terminated by a NEWLINE, to the standard output.

echo is useful for producing diagnostics in command files and for sending known data into a pipe, and for displaying the contents of environment variables.

For example, you can use echo to determine how many subdirectories below the root directory (/) is your current directory, as follows:

• echo your current-working-directory's full pathname

• pipe the output through tr to translate the path's embedded slash-characters into space-characters

• pipe that output through wc -w for a count of the names in your path.

  example% /usr/bin/echo "echo $PWD | tr '/' ' ' | wc -w"

See tr(1) and wc(1) for their functionality.

The shells csh(1), ksh(1), and sh(1), each have an echo built-in command, which, by default, will have precedence, and will be invoked if the user calls echo without a full pathname. /usr/ucb/echo and csh's echo() have an -n option, but do not understand back-slashed escape characters. sh's echo(), ksh's echo(), and /usr/bin/echo, on the other hand, understand the black-slashed escape characters, and ksh's echo() also understands \a as the audible bell character; however, these commands do not have an -n option.

选项

-n

Do not add the NEWLINE to the output.

属性

See attributes(5) for descriptions of the following attributes:

另请参见

csh(1), echo(1), ksh(1), sh(1), tr(1), wc(1), attributes(5)

附注

The -n option is a transition aid for BSD applications, and may not be supported in future releases.