Question

我是shell脚本的新手，并且使用man命令来处理我无法理解的一切。这是我的一段代码

$OUT="/try1.sh"
 if [ -a $OUT ]
 then
 rotate $OUT
 fi

在ksh中什么是-a做什么和什么是rotate命令，因为在ksh中没有用于旋转的man条目。

Answer 1

-a是[[ ]]或[ ]的条件表达式。它检查文件是否与-e相同但是是过时的版本。

如上所述：

A conditional expression is used with the [[ compound command to test attributes of files and to compare strings.  Field splitting and file name generation are not
performed on the words between [[ and ]].  Each expression can be constructed from one or more of the following unary or binary expressions:
string True, if string is not null.
-a file
       Same as -e below.  This is obsolete.

-e file
       True, if file exists.

对于您的脚本，它会检查/try1.sh是否存在。我还建议使用这种格式：

OUT="/try1.sh"          ## When assigning a value to a variable, don't include the dollar sign ($).
if [[ -a $OUT ]]; then  ## Use [[ ]]
    rotate "$OUT"       ## Quote your variables inside ""
fi

什么是ksh脚本中的-a和rotate命令

1 个答案: