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Bash 正则表达式比较十六进制字节 \x01 失败

tag-icon • tag-icon bash text-processing regular-expression
Bash 正则表达式比较十六进制字节 \x01 失败

当使用$'\x01'End-Of-String char 时，Bash 正则表达式无法正确比较。$所有其他字节值（似乎）比较正确。

使用 GNU bash 4.1.5(1)。这是一个错误，还是除了 之外还有其他方法以十六进制表示法表示字节$'\...'？ ...但这似乎不是符号，因为即使是文字 char 到文字 char 的比较也会失败。

$'\x01'仅当紧接在 End-Of-String 之前时才会发生此“失败” $。

这里有些例子：

echo 'non \x01 with ^ and $'
[[      3  =~ ^$'\x33'$ ]]; echo $?  # 0 
[[      3  =~ ^$'\063'$ ]]; echo $?  # 0 
[[ $'\x12' =~ ^$'\x12'$ ]]; echo $?  # 0 
[[ $'\002' =~ ^$'\x02'$ ]]; echo $?  # 0 

echo '\x01 with no ^ or $'
[[ $'\x01' =~  $'\x01'  ]]; echo $?  # 0 
[[ $'\x01' =~  $'\001'  ]]; echo $?  # 0 
[[       =~  $'\001'  ]]; echo $?  # 0   nb. Literal char does not render
[[       =~         ]]; echo $?  # 0   nb. Literal char does not render

echo '\x01 with ^ only'
[[ $'\x01' =~ ^$'\x01'  ]]; echo $?  # 0 
[[ $'\x01' =~ ^$'\001'  ]]; echo $?  # 0 
[[       =~ ^$'\001'  ]]; echo $?  # 0   nb. Literal char does not render
[[       =~ ^       ]]; echo $?  # 0   nb. Literal char does not render

echo '\x01 with ^ and $'
[[ $'\x01' =~ ^$'\x01'$ ]]; echo $?  # 1 
[[ $'\x01' =~ ^$'\001'$ ]]; echo $?  # 1 
[[       =~ ^$'\001'$ ]]; echo $?  # 1   nb. Literal char does not render
[[       =~ ^$      ]]; echo $?  # 1   nb. Literal char does not render

echo '\x01 with $ only'
[[ $'\x01' =~  $'\x01'$ ]]; echo $?  # 1 
[[ $'\x01' =~  $'\001'$ ]]; echo $?  # 1 
[[       =~  $'\001'$ ]]; echo $?  # 1   nb. Literal char does not render
[[       =~  $      ]]; echo $?  # 1   nb. Literal char does not render

echo '\x01 with $ only, but not adjacent to \x01'
[[ $'\x01'c =~  $'\x01'c$ ]]; echo $?  # 0 
[[ $'\x01'c =~  $'\001'c$ ]]; echo $?  # 0 
[[      c =~  $'\001'c$ ]]; echo $?  # 0   nb. Literal char does not render
[[      c =~  c$      ]]; echo $?  # 0   nb. Literal char does not render

答案1

是的，这是旧版本中的一个错误，已bash在 bash-4.2.14 中修复

这是使问题消失的提交;你可以随心所欲地利用它。

什么是CTLESC？你看，它是在syntax.has中定义的。#define CTLESC '\001'这是某种与扩张有关的内部逃避。看起来这个错误可能是你的\x01数据被解释为好像它是内部生成的CTLESC或类似的东西。

commit 25db9a70d4c2ba5c43d4167f231bdd8d760d5a06
Author: Chet Ramey <[email protected]>
Date:   Tue Nov 22 20:02:46 2011 -0500

    Bash-4.2 patch 14

diff --git a/patchlevel.h b/patchlevel.h
index 636be1c..04b423b 100644
--- a/patchlevel.h
+++ b/patchlevel.h
@@ -25,6 +25,6 @@
    regexp `^#define[   ]*PATCHLEVEL', since that's what support/mkversion.sh
    looks for to find the patch level (for the sccs version string). */

-#define PATCHLEVEL 13
+#define PATCHLEVEL 14

 #endif /* _PATCHLEVEL_H_ */
diff --git a/pathexp.c b/pathexp.c
index 42f21e4..f239956 100644
--- a/pathexp.c
+++ b/pathexp.c
@@ -196,7 +196,7 @@ quote_string_for_globbing (pathname, qflags)
    {
      if ((qflags & QGLOB_FILENAME) && pathname[i+1] == '/')
        continue;
-     if ((qflags & QGLOB_REGEXP) && ere_char (pathname[i+1]) == 0)
+     if (pathname[i+1] != CTLESC && (qflags & QGLOB_REGEXP) && ere_char (pathname[i+1]) == 0)
        continue;
      temp[j++] = '\\';
      i++;

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