BASH：转义字符串
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BASH: unescape string
提问by Christopher
Suppose I have the following string:
假设我有以下字符串：
"some\nstring\n..."
And it displays as one line when catted in bash. Further,
当在 bash 中 catted 时，它显示为一行。更远，
string_from_pipe | sed 's/\\/\/g' # does not work
| awk '{print some
string
}'
| awk '{s = s='some\nstring\n...'
printf '%b\n' "$s"
; print s}'
| awk '{s = some
string
...
; printf "%s",s}'
| echo $ s="some\nstring\n..."
$ echo "$s"
some\nstring\n...
| sed 's/\(.)//g'
# all have not worked.
How do I unescape this string such that it prints as:
我如何取消转义这个字符串，使其打印为：
$ printf "$s\n"
some
string
...
Or even displays that way inside a file?
或者甚至在文件中以这种方式显示？
采纳答案by Charles Duffy
POSIX shprovides printf %bfor just this purpose:
POSIX正是为此目的而sh提供printf %b的：
$ echo "$s" | sed 's/\n/\n/g'
some
string
...
...will emit:
...会发出：
$ echo "$s" | awk '{gsub(/\n/, "\n")} 1'
some
string
...
More to the point, the APPLICATION USAGE section of the POSIX spec for echoexplicitly suggests using printf %bfor this purpose rather than relying on optional XSI extensions.
更重要的是，POSIX 规范echo的 APPLICATION USAGE 部分明确建议printf %b为此目的使用，而不是依赖可选的 XSI 扩展。
回答by John1024
As you observed, echodoes not solve the problem:
正如您所观察到的，echo并不能解决问题：
${myvar//\n/$'\n'}
You haven't mentioned where you got that string or which escapes are in it.
你还没有提到你从哪里得到那个字符串或其中有哪些转义。
Using bash
使用 bash
If the escapes are ones supported by printf, then try:
如果转义是由 支持的printf，则尝试：
$ myvar='hello\nworld\nfoo'
$ echo "${myvar//\n/$'\n'}"
hello
world
foo
$
Using sed
使用 sed
$ s="some\nstring\n..." && echo -e "$s"
some
string
...
Using awk
使用 awk
-e enable interpretation of the following backslash escapes
[...]
\a alert (bell)
\b backspace
\c suppress further output
\e escape character
\f form feed
\n new line
\r carriage return
\t horizontal tab
\v vertical tab
\ backslash
##代码##nnn the character whose ASCII code is NNN (octal). NNN can be 0 to 3 octal digits
\xHH the eight-bit character whose value is HH (hexadecimal). HH can be one or two hex digits
回答by psmears
If you have the string in a variable (say myvar), you can use:
如果您在变量中有字符串（例如myvar），您可以使用：
For example:
例如：
##代码##(Note: it's usually safer to use printf %s <string>than echo <string>, if you don't have full control over the contents of <string>.)
（注意：如果您不能完全控制 . 的内容，则使用它通常printf %s <string>比更安全。）echo <string><string>
