Question

while read dir ev file; do
#do stuff
done

我无法找到解释的部分是＆＃34; read dir ev＆＃34;部分。我不熟悉bash。我主要做PHP和MySQL。谁能解释一下？

感谢。

Answer 1

简短版本是，它从输入中一次只需一行，并将其中的各个字段分配给变量。

read dir ev file将逐行读取行并期望每行包含3个项目。然后，它会将第一个项目分配给名为dir的变量，第二个项目分配给名为ev的变量，第三个项目分配给名为file的变量。

来自help read的输出：

（编辑：更可读的版本：http://ss64.com/bash/read.html）

read: read [-ers] [-a array] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-t timeout] [-u fd] [name ...]
    Read a line from the standard input and split it into fields.

    Reads a single line from the standard input, or from file descriptor FD
    if the -u option is supplied.  The line is split into fields as with word
    splitting, and the first word is assigned to the first NAME, the second
    word to the second NAME, and so on, with any leftover words assigned to
    the last NAME.  Only the characters found in $IFS are recognized as word
    delimiters.

    If no NAMEs are supplied, the line read is stored in the REPLY variable.

    Options:
      -a array  assign the words read to sequential indices of the array
                variable ARRAY, starting at zero
      -d delim  continue until the first character of DELIM is read, rather
                than newline
      -e                use Readline to obtain the line in an interactive shell
      -i text   Use TEXT as the initial text for Readline
      -n nchars return after reading NCHARS characters rather than waiting
                for a newline, but honor a delimiter if fewer than NCHARS
                characters are read before the delimiter
      -N nchars return only after reading exactly NCHARS characters, unless
                EOF is encountered or read times out, ignoring any delimiter
      -p prompt output the string PROMPT without a trailing newline before
                attempting to read
      -r                do not allow backslashes to escape any characters
      -s                do not echo input coming from a terminal
      -t timeout        time out and return failure if a complete line of input is
                not read withint TIMEOUT seconds.  The value of the TMOUT
                variable is the default timeout.  TIMEOUT may be a
                fractional number.  If TIMEOUT is 0, read returns success only
                if input is available on the specified file descriptor.  The
                exit status is greater than 128 if the timeout is exceeded
      -u fd             read from file descriptor FD instead of the standard input

    Exit Status:
    The return code is zero, unless end-of-file is encountered, read times out,
    or an invalid file descriptor is supplied as the argument to -u.

Bash脚本，请解释这个语法

1 个答案: