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如何在‘find’的‘-exec’属性中使用‘if’？

tag-icon • tag-icon command-line bash find
如何在‘find’的‘-exec’属性中使用‘if’？

我有一个包含多对文件的目录。每个非文本文件都有一个文本描述伙伴。例如，目录可能如下所示：

a.jpg
a.jpg.text
b.ogv
b.ogv.text
cd ef.JpG
cd ef.JpG.text

我想确认没有松散的文本文件（已删除内容的描述文件）。因此，我尝试执行以下操作：

find . -name '*.text' -exec if [ ! -f `basename -s .text {}` ]; then echo {}; fi \;

但是，现在我收到一个错误：

bash: syntax error near unexpected token `then'

答案1

您无法按照自己希望的方式在命令操作if内部使用它。这是因为以下原因：-execfind

  • 该-exec行动预期命令。这是从man find（我的终端的第 697 行某处）来的：
    -exec command ;
          Execute  command;  true  if 0 status is returned.  All following
          arguments to find are taken to be arguments to the command until
          an  argument  consisting of `;' is encountered.  The string `{}'
          is replaced by the current file name being processed  everywhere
          it occurs in the arguments to the command, not just in arguments
          where it is alone, as in some versions of find.  Both  of  these
          constructions might need to be escaped (with a `\') or quoted to
          protect them from expansion by the shell.  See the EXAMPLES sec‐
          tion for examples of the use of the -exec option.  The specified
          command is run once for each matched file.  The command is  exe‐
          cuted  in  the starting directory.   There are unavoidable secu‐
          rity problems surrounding use of the -exec  action;  you  should
          use the -execdir option instead.

    -exec command {} +
          This  variant  of the -exec action runs the specified command on
          the selected files, but the command line is built  by  appending
          each  selected file name at the end; the total number of invoca‐
          tions of the command will  be  much  less  than  the  number  of
          matched  files.   The command line is built in much the same way
          that xargs builds its command lines.  Only one instance of  `{}'
          is  allowed  within the command.  The command is executed in the
          starting directory.
  • if是不是您可能认为是命令，但shell 关键字type if.查看命令的输出。

现在，要实现您的愿望，您实际上不需要if在 内部使用-exec。只需在 内部进行测试-exec，然后使用-print（man find有关详细信息，请参阅）：

find . -name '*.text' -exec $SHELL -c '[ ! -f ${1%.*} ]' $SHELL '{}' ';' -print

另一种方法是使用 bash 脚本，如下所示：

find . -name '*.text' -exec my_if {} \;

在我的例子中，输出cat ~/bin/my_if如下：

#!/bin/bash
if [ ! -f $(basename -s .text "$1") ]; then echo "$1"; fi

最后，我认为所有使用 bash 的普通人都会使用：

for f in *.text; do if [ ! -f $(basename -s .text "$f") ]; then echo "$f"; fi; done

答案2

if以下是在子句中使用 in 的未优化方法exec：

find . -name '*.text' -exec sh -c \
    'if [ ! -f "$(dirname "$1")/$(basename "$1" .text)" ]; then echo == $1; fi' sh {} \;

这里有一个更好的方法，它不需要为每个文件启动一个 shell：

find . -name '*.text' -exec sh -c \
    'for i do if [ ! -f "${i%.text}" ]; then echo == $i; fi;done' sh {} +

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