Shell Builtin Command 「echo」

type echo

執行

$ type echo

顯示

echo is a shell builtin

執行

$ type -a echo

顯示

echo is a shell builtin
echo is /bin/echo

help echo

執行

$ help echo

顯示

echo: echo [-neE] [arg ...]
    Write arguments to the standard output.

    Display the ARGs, separated by a single space character and followed by a
    newline, on the standard output.

    Options:
      -n        do not append a newline
      -e        enable interpretation of the following backslash escapes
      -E        explicitly suppress interpretation of backslash escapes

    `echo' interprets the following backslash-escaped characters:
      \a        alert (bell)
      \b        backspace
      \c        suppress further output
      \e        escape character
      \E        escape character
      \f        form feed
      \n        new line
      \r        carriage return
      \t        horizontal tab
      \v        vertical tab
      \\        backslash
      \0nnn     the character whose ASCII code is NNN (octal).  NNN can be
        0 to 3 octal digits
      \xHH      the eight-bit character whose value is HH (hexadecimal).  HH
        can be one or two hex digits

    Exit Status:
    Returns success unless a write error occurs.

Exit Status

執行

$ echo

顯示

再執行

$ echo $?

顯示

0