bash 使用 sed 匹配包含换行符的字符串
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Match a string that contains a newline using sed
提问by Romeo Mihalcea
I have a string like this one:
我有一个这样的字符串：
#
pap
which basically translates to a \t#\n\tpapand I want to replace it with:
这基本上转化为 a \t#\n\tpap，我想用以下内容替换它：
#
pap
python
which translates to \t#\n\tpap\n\tpython.
这转化为\t#\n\tpap\n\tpython.
Tried this with sedin a lot of ways but it's not working maybe because seduses new lines in a different way. I tried with:
尝试sed了很多方法，但它不起作用可能是因为sed以不同的方式使用新行。我试过：
sed -i "s/\t#\n\tpap/\t#\tpython\n\tpap/" /etc/freeradius/sites-available/default
...and many different other ways with no result. Any idea how can I do my replace in this situation?
...以及许多不同的其他方式，但没有结果。知道在这种情况下我该如何更换吗？
采纳答案by Kent
try this line with gawk:
用 gawk 试试这一行：
awk -v RS="sed ':a;N;$!ba;s/\t#\n\tpap/NewString/g' file
" -v ORS="" '{gsub(/\t#\n\tpap/,"yourNEwString")}7' file
if you want to let sedhandle new lines, you have to read the whole file first:
如果你想让sed处理新行，你必须先阅读整个文件：
sed '/^\t#$/{n;/^\tpap$/{p;s//\tpython/}}' file
回答by potong
This might work for you (GNU sed):
这可能对你有用（GNU sed）：
sed '/^\t#$/ {n;/^\tpap$/a\tpython'$'\n''}' file
If a line contains only \t#print it, then if the next line contains only \tpapprint it too, then replace that line with \tpythonand print that.
如果一行只包含\t#打印它，那么如果下一行也只包含\tpap打印它，则将该行替换为\tpython并打印。
回答by mklement0
A GNU sedsolution that doesn't require reading the entire file at once:
一个GNUsed的解决方案，不需要读取整个文件一次：
sed '/^'$'\t''#$/ {n; /^'$'\t''pap$/ s//&\'$'\n\t'python'/;}' file
/^\t#$/matches comment-only lines (matching\t#exactly), in which case (only) the entire{...}expression is executed:nloads and prints the nextline./^\tpap/matches that next line against\tpapexactly.- in case of a match,
a\\tpythonwill then output\n\tpythonbefore the followingline is read - note that the spliced-in newline ($'\n') is required to signal the end of the text passed to theacommand (you can alternatively use multiple-eoptions).
/^\t#$/匹配仅注释行（\t#完全匹配），在这种情况下（仅）执行整个{...}表达式：n加载并打印下一行。/^\tpap/与下一行\tpap完全匹配。- 如果匹配，
a\\tpython将\n\tpython在读取下一行之前输出- 请注意，需要拼接换行符 ($'\n') 来表示传递给a命令的文本的结尾（您也可以使用多个-e选项）。
(As an aside: with BSD sed(OS X), it gets cumbersome, because
（顺便说一句：对于BSD sed(OS X)，它变得很麻烦，因为
- Control chars. such as
\nand\taren't directly supported and must be spliced in as ANSI C-quoted literals. Leading whitespace is invariably stripped from the text argument to the
acommand, so a substitution approach must be used:s//&\'$'\n\t'python'/replaces thepapline with itself plusthe line to append:sed '/^'$'\t''#$/ {n; /^'$'\t''pap$/ s//&\'$'\n\t'python'/;}' file
- 控制字符。例如
\n和\t不受直接支持，必须拼接为 ANSI C 引用的文字。 前导空格总是从
a命令的文本参数中去除，因此必须使用s//&\'$'\n\t'python'/替换方法：将pap行替换为自身加上要附加的行：awk '{print} /^\t#$/ {f=1;next} f && /^\tpap$/ {print "\tpython"} {f=0}' file
)
)
An awksolution(POSIX-compliant) that also doesn't require reading the entire file at once:
也不需要一次读取整个文件的awk解决方案（符合 POSIX 标准）：
in=$'\t#\n\tpap\n' # input string
echo "${in/$'\t#\n\tpap\n'/$'\t#\n\tpap\n\tpython\n'}"
{print}: prints every input line/^\t#$/ {f=1;next}: sets flagf(for 'found') to1if a comment-only line (matching\t#exactly) is found and moves on to the next line.f && /^\tpap$/ {print "\tpython"}: if a line is preceded by a comment line and matches\tpapexactly, outputs extra line\tpython.{f=0}: resets the flag that indicates a comment-only line.
{print}: 打印每个输入行/^\t#$/ {f=1;next}:如果f找到1仅注释行（\t#完全匹配）并移至下一行，则设置标志（用于 'found'）。f && /^\tpap$/ {print "\tpython"}: 如果一行前面是注释行并且\tpap完全匹配，则输出额外的 line\tpython。{f=0}: 重置指示仅注释行的标志。
回答by mklement0
A couple of pure bashsolutions:
几个纯粹的bash解决方案：
Concise, but somewhat fragile, using parameter expansion:
简洁，但有点脆弱，使用参数扩展：
in=$'\t#\n\tpap' # input string
# Search string and string to append after.
search=$'\t#\n\tpap'
append=$'\n\tpython'
out=$in # Initialize output string to input string.
if [[ $in =~ ^(.*$'\n')?("$search")($'\n'.*)?$ ]]; then # perform regex matching
out=${out/$search/$search$append} # replace match with match + appendage
fi
echo "$out"
- Parameter expansion only supports patterns(wildcard expressions) as search strings, which limits the matching abilities:
- Here the assumption is made that
papis followed by\n, whereas no assumption is made about what precedes\t#, potentially resulting in false positives. - If the assumption could be made that
\t#\n\tpapis always enclosedin\n,echo "${in/$'\n\t#\n\tpap\n'/$'\n\t#\n\tpap\n\tpython\n'}"would work robustly; otherwise, see below.
- 参数扩展仅支持模式（通配符表达式）作为搜索字符串，这限制了匹配能力：
- 这里的假设是在
pap之后进行\n，而没有对 之前的内容进行假设\t#，这可能会导致误报。 - 如果假设可以作出
\t#\n\tpap总是封闭在\n，echo "${in/$'\n\t#\n\tpap\n'/$'\n\t#\n\tpap\n\tpython\n'}"将有力的工作; 否则，请参见下文。
Robust, but verbose, using the =~operator for regex matching:
健壮但冗长，使用=~运算符进行正则表达式匹配：
The =~operator supports extended regular expressionson the right-hand side and thus allows more flexible and robust matching:
所述=~操作者支撑件延伸的正则表达式的右手侧，并因此允许更灵活和强大的匹配：
