如何测试Bash文件中是否存在字符串？

我有一个包含目录名称的文件：

my_list.txt ：

/tmp
/var/tmp

如果该名称已存在于文件中，我会在添加目录名称之前检入Bash。

---

grep -Fxq "$FILENAME" my_list.txt

如果名称被找到，则退出状态为0（真），否则为1（假），因此：

if grep -Fxq "$FILENAME" my_list.txt
then
    # code if found
else
    # code if not found
fi

以下是grep手册页的相关部分：

grep [options] PATTERN [FILE...]

-F, --fixed-strings
       Interpret PATTERN as a list of fixed strings, separated by  new-
       lines, any of which is to be matched.

-x, --line-regexp
       Select only those matches that exactly match the whole line.

-q, --quiet, --silent
       Quiet; do not write anything to standard output.  Exit  immedi-
       ately  with  zero status if any match is found, even if an error
       was detected.  Also see the -s or --no-messages option.

---

关于以下解决方案：

grep -Fxq "$FILENAME" my_list.txt

如果你想知道（就像我做过的那样） -Fxq意思是简单的英语F会影响PATTERN的解释方式（固定字符串而不是正则表达式）， x匹配整行， q shhhhh ...最小打印

从man文件中：

-F, --fixed-strings

          Interpret  PATTERN  as  a  list of fixed strings, separated by newlines, any of which is to be matched.
          (-F is specified by POSIX.)
-x, --line-regexp
          Select only those matches that exactly match the whole line.  (-x is specified by POSIX.)
-q, --quiet, --silent
          Quiet; do not write anything to standard output.  Exit immediately with zero status  if  any  match  is
          found,  even  if  an error was detected.  Also see the -s or --no-messages option.  (-q is specified by
          POSIX.)

---

我脑海中的三种方法：

1）在路径中测试一个名称（我不确定这可能是你的情况）

ls -a "path" | grep "name"

2）对文件中的字符串进行简短测试

grep -R "string" "filepath"

3）使用正则表达式更长的bash脚本：

#!/bin/bash

declare file="content.txt"
declare regex="s+strings+"

declare file_content=$( cat "${file}" )
if [[ " $file_content " =~ $regex ]] # please note the space before and after the file content
    then
        echo "found"
    else
        echo "not found"
fi

exit

如果您必须使用循环测试文件内容中的多个字符串 ，例如在任何cicle上更改正则表达式，这应该会更快 。

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