如何使用Bash shell测试文件中是否存在字符串？ [英] How to test if string exists in file with Bash shell?

问题描述

我有一个包含目录名称的文件：

I have a file that contains directory names:

my_list.txt ：

/tmp
/var/tmp

如果文件中已经存在该名称，我想在Bash中检查一下目录名。

I'd like to check in Bash before I'll add a directory name if that name already exists in the file.

推荐答案

grep -Fxq "$FILENAME" my_list.txt

如果找到名称，退出状态为0（true），否则为1（false），所以：

The exit status is 0 (true) if the name was found, 1 (false) if not, so:

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

以下是 grep 的手册页：

Here are the relevant sections of the man page for grep:

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.

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