在Bash中是否有需要转义的字符的综合列表?仅仅用sed可以检查吗?
特别是，我正在检查%是否需要转义。我试着
echo "h%h" | sed 's/%/i/g'
并工作良好，没有逃脱%。这是否意味着%不需要转义?这是检查必要性的好方法吗?
更一般的是:它们是shell和bash中转义的相同字符吗?
当前回答
使用打印'%q'技术，我们可以运行一个循环来找出哪些字符是特殊的:
#!/bin/bash
special=$'`!@#$%^&*()-_+={}|[]\\;\':",.<>?/ '
for ((i=0; i < ${#special}; i++)); do
char="${special:i:1}"
printf -v q_char '%q' "$char"
if [[ "$char" != "$q_char" ]]; then
printf 'Yes - character %s needs to be escaped\n' "$char"
else
printf 'No - character %s does not need to be escaped\n' "$char"
fi
done | sort
它给出如下输出:
No, character % does not need to be escaped
No, character + does not need to be escaped
No, character - does not need to be escaped
No, character . does not need to be escaped
No, character / does not need to be escaped
No, character : does not need to be escaped
No, character = does not need to be escaped
No, character @ does not need to be escaped
No, character _ does not need to be escaped
Yes, character needs to be escaped
Yes, character ! needs to be escaped
Yes, character " needs to be escaped
Yes, character # needs to be escaped
Yes, character $ needs to be escaped
Yes, character & needs to be escaped
Yes, character ' needs to be escaped
Yes, character ( needs to be escaped
Yes, character ) needs to be escaped
Yes, character * needs to be escaped
Yes, character , needs to be escaped
Yes, character ; needs to be escaped
Yes, character < needs to be escaped
Yes, character > needs to be escaped
Yes, character ? needs to be escaped
Yes, character [ needs to be escaped
Yes, character \ needs to be escaped
Yes, character ] needs to be escaped
Yes, character ^ needs to be escaped
Yes, character ` needs to be escaped
Yes, character { needs to be escaped
Yes, character | needs to be escaped
Yes, character } needs to be escaped
有些结果，看起来有点可疑。获得@CharlesDuffy在这方面的投入会很有趣。
其他回答
有两个简单而安全的规则，它们不仅可以在sh中工作，还可以在bash中工作。
1. 把整个字符串放在单引号中
这适用于所有字符，除了单引号本身。若要转义单引号，请关闭它前面的引号，插入单引号，然后重新打开引号。
'I'\''m a s@fe $tring which ends in newline
'
Sed命令:Sed -e "s/'/'\\\\ " /g;1年代/ ^ / /;\ s / \ /美元/”
2. 用反斜杠转义每个char
这适用于除换行符以外的所有字符。换行符使用单引号或双引号。空字符串仍然必须处理-替换为""
\I\'\m\ \a\ \s\@\f\e\ \$\t\r\i\n\g\ \w\h\i\c\h\ \e\n\d\s\ \i\n\ \n\e\w\l\i\n\e"
"
Sed命令:Sed -e 's/./\\&/g;1 {$ s / ^ $ / "};1 ! s / ^ /”;美元! s / /美元“/”。
2 b。更可读的版本2
有一组简单安全的字符，比如[a-zA-Z0-9，]。_+:@%/-]，可以不转义，以使其更具可读性
I\'m\ a\ s@fe\ \$tring\ which\ ends\ in\ newline"
"
sed命令:LC_ALL = C sed - e ' s / [^ a-zA-Z0-9 ,._+@%/-]/\\&/ g;1 {$ s / ^ $ / "};1 ! s / ^ /”;美元! s / /美元“/”。
注意，在sed程序中，不能知道输入的最后一行是否以换行符字节结束(除非换行符为空)。这就是为什么上面的sed命令都假设它不存在。您可以手动添加带引号的换行符。
注意，外壳变量仅为POSIX意义上的文本定义。没有定义如何处理二进制数据。对于重要的实现，二进制除了NUL字节(因为变量是用C字符串实现的，意味着被用作C字符串，即程序参数)，但您应该切换到“二进制”语言环境，例如latin1。
(你可以通过阅读sh的POSIX规范来验证规则。对于bash，查看@AustinPhillips链接的参考手册)
在Bourne或POSIX shell中需要转义的角色与Bash不同。通常(very) Bash是这些shell的超集，所以在shell中转义的任何内容都应该在Bash中转义。
一个很好的一般规则是“如果有疑问，逃避它”。但是转义某些字符会赋予它们特殊的含义，比如\n。这些在引用和回声下的man bash页面中列出。
除此之外，转义任何非字母数字的字符更安全。我不知道一个明确的清单。
手册页在某个地方列出了它们，但不是在一个地方。学习语言，那是必胜之道。
其中一个让我大吃一惊的是!这是Bash(和csh)中的一个特殊字符(历史扩展)，但在Korn shell中不是。即使是回音“Hello world!”也会出问题。像往常一样，使用单引号就去掉了特殊含义。
可以作为shell输入重用的格式
编辑2021年2月:bash ${var@Q}
在bash下，你可以使用参数扩展的@命令来存储变量内容，用于参数转换:
${parameter@operator} Parameter transformation. The expansion is either a transforma‐ tion of the value of parameter or information about parameter itself, depending on the value of operator. Each operator is a single letter: Q The expansion is a string that is the value of parameter quoted in a format that can be reused as input. ... A The expansion is a string in the form of an assignment statement or declare command that, if evaluated, will recreate parameter with its attributes and value.
示例:
$ var=$'Hello\nGood world.\n'
$ echo "$var"
Hello
Good world.
$ echo "${var@Q}"
$'Hello\nGood world.\n'
$ echo "${var@A}"
var=$'Hello\nGood world.\n'
旧的答案
有一个特殊的printf格式指令(%q)用于这种请求:
Printf [-v var] format[参数] %q导致printf输出相应的参数 可以作为shell输入重用的格式。
一些样品:
read foo
Hello world
printf "%q\n" "$foo"
Hello\ world
printf "%q\n" $'Hello world!\n'
$'Hello world!\n'
这也可以通过变量来使用:
printf -v var "%q" "$foo
"
echo "$var"
$'Hello world\n'
快速检查所有(128)ascii字节:
注意，从128到255的所有字节都必须转义。
for i in {0..127} ;do
printf -v var \\%o $i
printf -v var $var
printf -v res "%q" "$var"
esc=E
[ "$var" = "$res" ] && esc=-
printf "%02X %s %-7s\n" $i $esc "$res"
done |
column
这必须呈现如下内容:
00 E '' 1A E $'\032' 34 - 4 4E - N 68 - h
01 E $'\001' 1B E $'\E' 35 - 5 4F - O 69 - i
02 E $'\002' 1C E $'\034' 36 - 6 50 - P 6A - j
03 E $'\003' 1D E $'\035' 37 - 7 51 - Q 6B - k
04 E $'\004' 1E E $'\036' 38 - 8 52 - R 6C - l
05 E $'\005' 1F E $'\037' 39 - 9 53 - S 6D - m
06 E $'\006' 20 E \ 3A - : 54 - T 6E - n
07 E $'\a' 21 E \! 3B E \; 55 - U 6F - o
08 E $'\b' 22 E \" 3C E \< 56 - V 70 - p
09 E $'\t' 23 E \# 3D - = 57 - W 71 - q
0A E $'\n' 24 E \$ 3E E \> 58 - X 72 - r
0B E $'\v' 25 - % 3F E \? 59 - Y 73 - s
0C E $'\f' 26 E \& 40 - @ 5A - Z 74 - t
0D E $'\r' 27 E \' 41 - A 5B E \[ 75 - u
0E E $'\016' 28 E \( 42 - B 5C E \\ 76 - v
0F E $'\017' 29 E \) 43 - C 5D E \] 77 - w
10 E $'\020' 2A E \* 44 - D 5E E \^ 78 - x
11 E $'\021' 2B - + 45 - E 5F - _ 79 - y
12 E $'\022' 2C E \, 46 - F 60 E \` 7A - z
13 E $'\023' 2D - - 47 - G 61 - a 7B E \{
14 E $'\024' 2E - . 48 - H 62 - b 7C E \|
15 E $'\025' 2F - / 49 - I 63 - c 7D E \}
16 E $'\026' 30 - 0 4A - J 64 - d 7E E \~
17 E $'\027' 31 - 1 4B - K 65 - e 7F E $'\177'
18 E $'\030' 32 - 2 4C - L 66 - f
19 E $'\031' 33 - 3 4D - M 67 - g
其中第一个字段是字节的十六进制值，第二个字段包含E，如果字符需要转义，第三个字段显示字符的转义表示。
为什么,?
您可能会看到一些不总是需要转义的字符，如，，}和{。
所以不是总是，而是有时:
echo test 1, 2, 3 and 4,5.
test 1, 2, 3 and 4,5.
or
echo test { 1, 2, 3 }
test { 1, 2, 3 }
但医改:
echo test{1,2,3}
test1 test2 test3
echo test\ {1,2,3}
test 1 test 2 test 3
echo test\ {\ 1,\ 2,\ 3\ }
test 1 test 2 test 3
echo test\ {\ 1\,\ 2,\ 3\ }
test 1, 2 test 3
使用打印'%q'技术，我们可以运行一个循环来找出哪些字符是特殊的:
#!/bin/bash
special=$'`!@#$%^&*()-_+={}|[]\\;\':",.<>?/ '
for ((i=0; i < ${#special}; i++)); do
char="${special:i:1}"
printf -v q_char '%q' "$char"
if [[ "$char" != "$q_char" ]]; then
printf 'Yes - character %s needs to be escaped\n' "$char"
else
printf 'No - character %s does not need to be escaped\n' "$char"
fi
done | sort
它给出如下输出:
No, character % does not need to be escaped
No, character + does not need to be escaped
No, character - does not need to be escaped
No, character . does not need to be escaped
No, character / does not need to be escaped
No, character : does not need to be escaped
No, character = does not need to be escaped
No, character @ does not need to be escaped
No, character _ does not need to be escaped
Yes, character needs to be escaped
Yes, character ! needs to be escaped
Yes, character " needs to be escaped
Yes, character # needs to be escaped
Yes, character $ needs to be escaped
Yes, character & needs to be escaped
Yes, character ' needs to be escaped
Yes, character ( needs to be escaped
Yes, character ) needs to be escaped
Yes, character * needs to be escaped
Yes, character , needs to be escaped
Yes, character ; needs to be escaped
Yes, character < needs to be escaped
Yes, character > needs to be escaped
Yes, character ? needs to be escaped
Yes, character [ needs to be escaped
Yes, character \ needs to be escaped
Yes, character ] needs to be escaped
Yes, character ^ needs to be escaped
Yes, character ` needs to be escaped
Yes, character { needs to be escaped
Yes, character | needs to be escaped
Yes, character } needs to be escaped
有些结果，看起来有点可疑。获得@CharlesDuffy在这方面的投入会很有趣。
为了不让别人不得不RTFM…在bash中:
用双引号括起来的字符会保留引号内所有字符的文字值，除了$、'、\和(当启用历史扩展时)!
.．.所以如果你转义了这些(当然还有引用本身)，你可能就没事了。
如果你采取更保守的“当有疑问时，转义它”的方法，应该可以通过不转义标识符字符(即ASCII字母、数字或“_”)来避免获得具有特殊含义的字符。这是非常不可能的(即在一些奇怪的posix shell中)有特殊的含义，因此需要转义。
