bash 如何使用 tr 替换 '--' 字符串
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How do I use tr to substitute '--' string
提问by Guy
I have an output:
我有一个输出：
--
out1
--
out2
--
out3
I want to get the output:
我想得到输出：
out1
out2
out3
I thought of using:
我想过使用：
tr '--' ''
but it doesn't recognize '--' to be the first string I want to substitute. How do I solve this?
但它不承认 '--' 是我想替换的第一个字符串。我该如何解决这个问题？
回答by Amro
cat file | sed '/^--/d'
回答by Jerry Coffin
Why not use grep -v "^--$" yourfile.txt?
为什么不使用grep -v "^--$" yourfile.txt？
回答by ghostdog74
another way with awk
awk 的另一种方式
awk '!/^--$/' file
回答by Paused until further notice.
The best you can do with tris delete the hyphens leaving blank lines. The best way to do what you want is Amro's answerusing sed. It's important to remember that trdeals with lists of characters rather than multi-character strings so there's no point in putting two hyphens in your parameters.
您能做的最好的事情tr是删除连字符，留下空行。做你想要什么，最好的办法是荷银的答案使用sed。重要的是要记住，它tr处理的是字符列表而不是多字符串，因此在参数中放置两个连字符是没有意义的。
$ tr -d "-" < textfile
out1
out2
out3
However, in order to have trhandle hyphens and additional characters, you have to terminate the options using --or put the hyphen after the last character. Let's say you want to get rid of hyphens and letter-o:
但是，为了tr处理连字符和附加字符，您必须使用--或将连字符放在最后一个字符之后终止选项。假设您想去掉连字符和字母 o：
$ tr -d "-o" < textfile
tr: invalid option -- 'o'
Try ‘tr --help' for more information.
$ tr -d -- "-o" < textfile
ut1
ut2
ut3
$ tr -d "o-" < textfile
ut1
ut2
ut3
It's often a good idea to use the --option terminator when the character list is in a variable so bad data doesn't create errors unnecessarily. This is true for commands other than tras well.
--当字符列表在变量中时使用选项终止符通常是个好主意，这样坏数据就不会产生不必要的错误。这适用于其他命令tr。
tr -d -- "$charlist" < "$file"
回答by VNS
You can do the same thing with grepas well:
你也可以做同样的事情grep：
cat filename |grep -v "\--"
