I have string: this is a [\"sample\"] sample\'s.
What would be the correct way to remove backslashes from the double quote, preserving the double quote.
Expected output: this is a ["sample"] sample\'s.
I've tested: sed -i 's/\\\"//g' file.txt which is removing the "
Your command is almost correct. You just forgot to substitute with a double quote:
sed -i 's/\\"/"/g' file.txt
sed's s command substitutes the first part (between / here) with the second part. The g flag repeats the operation throughout the line. Your mistake was that the second part was empty, thus effectively deleting the whole \" string.
BTW, escaping the double quote is not necessary since your sed command is inside single quotes.
Related
I need use sed into bash script, for add lines after any line numer of script with some pair of values (below work)
sed -i.bak '14i\some_text=some_text' file
But I need on script bash (sh) for expand variables (below not work)
sed -i.bak '$number_linei\$var1=$var2' $var3
Just use double quotes instead of single quotes. You'll also need to use {} to delimit the number_line variable correctly and escape the \, too.
sed -i.bak "${number_line}i\\$var1=$var2" $var3
I'd personally prefer to see all of the variables use the {}, ending up with something like:
sed -i.bak "${number_line}i\\${var1}=${var2}" ${var3}
Change single quotes to double quotes:
man bash:
Enclosing characters in single quotes preserves the literal value of
each character within the quotes.
Enclosing characters in double quotes preserves the literal value of
all characters within the quotes, with the exception of $, `, \, and,
when history expansion is enabled, !. The characters $ and ` retain
their special meaning within double quotes.
I need use sed into bash script, for add lines after any line numer of script with some pair of values (below work)
sed -i.bak '14i\some_text=some_text' file
But I need on script bash (sh) for expand variables (below not work)
sed -i.bak '$number_linei\$var1=$var2' $var3
Just use double quotes instead of single quotes. You'll also need to use {} to delimit the number_line variable correctly and escape the \, too.
sed -i.bak "${number_line}i\\$var1=$var2" $var3
I'd personally prefer to see all of the variables use the {}, ending up with something like:
sed -i.bak "${number_line}i\\${var1}=${var2}" ${var3}
Change single quotes to double quotes:
man bash:
Enclosing characters in single quotes preserves the literal value of
each character within the quotes.
Enclosing characters in double quotes preserves the literal value of
all characters within the quotes, with the exception of $, `, \, and,
when history expansion is enabled, !. The characters $ and ` retain
their special meaning within double quotes.
I'm having a directory with many files having special characters and spaces. I want to perform an operation with all these files so I'm trying to store all filenames in a list.txt and then run the command with this list.
The special characters in my list are & []'.
So basically I want to use sed to replace each occurence with \ + the character in question.
E.g. : filename .txt => filename\ .txt etc...
The thing is I have trouble handling apostrophes.
Here is my command as of now :
ls | sed 's/\ /\\ /g' | sed 's/\&/\\&/g' | sed "s/\'/\\'/g" | sed 's/\[/\\[/g' | sed 's/\]/\\]/g'
At first I had issues with, I believe, the apostrophes in the string command in conflict with the apostrophes surrounding the string. So I used double quotes instead, but it still doesn't work.
I've tried all these and nothing worked :
sed "s/\'/\\'/g" (escaping the apostrophe)
sed "s/'/\'/g" (escaping nothing)
sed "s/'/\\'/g" (escaping the backslash)
sed 's/"'"/\"'"/g' (double quoting single quote)
As a disclaimer, I must say, I'm completely new to sed. I just run my first sed command today, so maybe I'm doing something wrong I didn't realize.
PS : I've seen those thread, but no answer worked for me :
https://unix.stackexchange.com/questions/157076/how-to-remove-the-apostrophe-and-delete-the-space
How to replace to apostrophe ' inside a file using SED
This may do:
cat file
avbadf
test&rr
more [ yes
this ]
and'df
sed -r 's/(\x27|&|\[|\])/\\\1/g' file
avbadf
test\&rr
more \[ yes
this \]
and\'df
\x27 is equal to singe quote '
\x22 is equal to double quote "
Whoops, I found the answer to my question. Here is the working input :
sed "s/'/\\\'/g"
This will effectively replace any ' with \'.
However I'm having trouble understanding exactly what's happening here.
So if I understand correctly, we are escaping the backslash and the apostrophe in the replacement string. Now, if somebody could answer some those, I would be grateful :
Why don't we need to escape the first quote (the one in the pattern to find) ?
Why do we have to escape the backslash whereas for the other characters, there's no need ?
Why do we need to escape the second quote (the one in the replacement string) ?
I think all of your sed matches actually need that replacement pattern. This one seems to work for all examples:
ls | sed "s/\ /\\\ /g" | sed "s/\&/\\\&/g" | sed "s/\[/\\\[/g" | sed "s/\]/\\\]/g" | sed "s/'/\\\'/g"
So it is s/regex/replacement/command and 'regex' and 'replacement' have different sets of special characters.
The only one that's different is s/'/\\\'/g and there only because I don't believe there is any special ' character on the regex expression. There is some obscure \' special character in the replacement expression, for matching buffer ends in multi-line mode, accord to the docs. That might be why it needs an escape in the replacement side, but not in the regex side.
For example, \5 is a special character in the replacement expression, so to replace:
filename5.txt -> filename\5.txt
You would also need, as with apostrophe:
sed "s/5/\\\5/g"
It probably has to do with the mysterious inner works of sed parsing, it might read from right to left or something.
Please try the following:
sed 's/[][ &'\'']/\\&/g' file
By using the same example by #Jotne, the result will be:
gavbadf
gtest\&rr
gmore\ \[\ yes
gthis\ \]
gand\'df
[How it works]
The regex part in the sed s command above just defines a character
class of & []', which should be escaped with a backslash.
The right square bracket ] does not need escaping when put
immediately after the left square bracket [.
The obfuscating part will be the handling of a single quote.
We cannot put a single quote within single quotes even if we escape it.
The workaround is as follows: Say we have an assignment str='aaabbb'.
To put a single quote between "aaa" and "bbb", we can say as
str='aaa'\''bbb'.
It may look puzzling but it just concatenates the three sequences;
1) to close the single-quoted string as 'aaa'.
2) to put a single quote with an escaping backslash as \'.
3) to restart the single-quoted string as 'bbb'.
Hope this helps.
I want to replace a string ip_ttl="1" with ip_ttl="2" using sed.
I've tried sed -i "s/ip_ttl="1"/ip_ttl="2"/g" - but its not working.
Please help!
Put your sed code inside single quotes, because your code already contains double quotes.
sed -i 's/ip_ttl="1"/ip_ttl="2"/g' file
If you put your code within two double quotes, sed would terminate the program once another double quote was reached. So " before 1 was reached, it would consider as the end and terminates the program.
Update:
If the number always changes then it's better to define the pattern which matches any number.
sed -i 's/ip_ttl="[0-9]\+"/ip_ttl="2"/g' file
If you are using quotation marks in your pattern either escape double quotes in pattern:
sed -i "s/ip_ttl=\"1\"/ip_ttl=\"2\"/g"
or enclose whole pattern in single quotes:
sed -i 's/ip_ttl="1"/ip_ttl="2"/g'
Alternatively you can escape the quotation marks
sed -i "s/ip_ttl=\"1\"/ip_ttl=\"2\"/g" file
Sometimes that's useful because you have both single and double quotes in a string you're selecting for.
I need use sed into bash script, for add lines after any line numer of script with some pair of values (below work)
sed -i.bak '14i\some_text=some_text' file
But I need on script bash (sh) for expand variables (below not work)
sed -i.bak '$number_linei\$var1=$var2' $var3
Just use double quotes instead of single quotes. You'll also need to use {} to delimit the number_line variable correctly and escape the \, too.
sed -i.bak "${number_line}i\\$var1=$var2" $var3
I'd personally prefer to see all of the variables use the {}, ending up with something like:
sed -i.bak "${number_line}i\\${var1}=${var2}" ${var3}
Change single quotes to double quotes:
man bash:
Enclosing characters in single quotes preserves the literal value of
each character within the quotes.
Enclosing characters in double quotes preserves the literal value of
all characters within the quotes, with the exception of $, `, \, and,
when history expansion is enabled, !. The characters $ and ` retain
their special meaning within double quotes.