以正则表达式模式转义bash变量包含的字符

发布时间：2020-12-14 05:56:31 所属栏目：百科来源：网络整理

导读：在我的bash脚本中,我正在尝试执行以下 Linux命令： sed -i "/$data_line/ d" $data_dir $data_line由用户输入,它可能包含可能制动正则表达式的特殊字符. 在执行sed命令之前,如何在$data_line中转义所有可能的特殊字符？解决方法您可以使用此技术来保护选择

在我的bash脚本中,我正在尝试执行以下 Linux命令：

sed -i "/$data_line/ d" $data_dir

$data_line由用户输入,它可能包含可能制动正则表达式的特殊字符.
在执行sed命令之前,如何在$data_line中转义所有可能的特殊字符？

解决方法

您可以使用此技术来保护选择器.下面标有“*****”的行是重要的行.其他人主要用于测试和演示.关键是使用未出现在用户输入中的字符来分隔选择器地址.

data_line='.*/ s/GOLD/LEAD/g;b;/.*'    # scary user input
candidates='/:.|@#%^&;,!~abcABC'       # *****   # (make it as long as you like)
char=$(echo "$candidates" | tr -d "$data_line")    # *****
char=${char:0:1}   # ***** choose the first candidate that doesn't appear in the user input

if [ -z "$char" ]    # ***** this test checks for exhaustion of the candidate character set
then
    echo "Unusable user input. Recommendation: cigarette and blindfold."
    exit 1
fi

# test without protection
excitement="GOLD,I tell you,thar's GOLD in them thar hills!" 
echo "$excitement" | sed "/$data_line/ d"
# output: "LEAD,thar's LEAD in them thar hills!"

# test WITH protection
echo "$excitement" | sed "${char}${data_line}${char} d"    # *****
# output: "GOLD,thar's GOLD in them thar hills!"

# test WITH protection and useful user input
data_line="secret"
mystery="The secret map is tucked in a hidden compartment in my saddle bag."
echo -e "$excitementn$mystery" | sed "${char}${data_line}${char} d"
# output: "GOLD,thar's GOLD in them thar hills!"

（编辑：李大同）

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