Replacing strings with special characters with linux sed - linux

I've read lots of posts to understand how to correctly escape white spaces and special characters inside strings using sed, but still i can't make it, here's what i'm trying to achieve.
I have a file containing the some strings like this one:
JAVA_OPTS="$JAVA_OPTS -Dorg.apache.catalina.jsessionid=some_value"
and i'm trying to replace 'some_value' using the following:
sed -i "s/^\(JAVA_OPTS=\"\$JAVA_OPTS[ \t]*-Dorg\.apache\.catalina\.jsessionid*=\s*\).*\$/\1$DORG_APACHE_CATALINA_JSESSIONID/" $JBOSS_CONFIGURATION/jboss.configuration
$JBOSS_CONFIGURATION is a variable containing an absolute Linux path.
jboss.configuration is a file i'm pointing as the target for replace
operations.
$DORG_APACHE_CATALINA_JSESSIONID contains the value i want instead
of 'some_value'.
Please note that the pattern:
JAVA_OPTS="$JAVA_OPTS -D
Is always present, and org.apache.catalina.jsessionid is an example of a variable value i'm trying to replace with this script.
What's missing/wrong ? i tried also escaping whitespaces using \s without success,
and echoing the whole gives me the following:
echo "s/^\(JAVA_OPTS=\"\$JAVA_OPTS[ \t]*-Dorg\.apache\.catalina\.jsessionid*=\s*\).*\$/\1$DORG_APACHE_CATALINA_JSESSIONID/"
s/^\(JAVA_OPTS="$JAVA_OPTS[ \t]*-Dorg\.apache\.catalina\.jsessionid*=\s*\).*$/\1/
is echo interpreting the search pattern as sed does ?
any info/help/alternative ways of doing it are highly welcome,
thank you all

echo 'JAVA_OPTS="$JAVA_OPTS -Dorg.apache.catalina.jsessionid=some_value"' | (export DORG_APACHE_CATALINA_JSESSIONID=FOO/BAR/FOOBAR; sed "s/^\(JAVA_OPTS=\"\$JAVA_OPTS[ \t]*-Dorg\.apache\.catalina\.jsessionid*=\s*\).*\$/\1${DORG_APACHE_CATALINA_JSESSIONID////\/}\"/")
Note the bash expansion (in order to escape any / that may trip up sed) and the extra \" after $DORG_APACHE_CATALINA_JSESSIONID in order to properly close the double quote. Other than that your sed expression works for me and the above command outputs the follwoing result:
JAVA_OPTS="$JAVA_OPTS -Dorg.apache.catalina.jsessionid=FOO/BAR/FOOBAR"

You can use sed like this:
sed -r '/\$JAVA_OPTS -D/{s/^(.+=).*$/\1'"$DORG_APACHE_CATALINA_JSESSIONID"'/;}' $JBOSS_CONFIGURATION/jboss.configuration

You can specify a pattern that'll match the desired string rather than trying to specify it exactly.
The following should work for you:
sed -i 's#^\(JAVA_OPTS.*Dorg.apache.catalina.jsessionid\)=\([^"]*\)"#\1='"$DORG_APACHE_CATALINA_JSESSIONID"'"#' $JBOSS_CONFIGURATION/jboss.configuration

sed 's/=\w.*$/='"$DORG_APACHE_CATALINA_JSESSIONID"'/' $JBOSS_CONFIGURATION/jboss.configuration

Related

How to keep dollar sign within sed in the bash script?

I am trying to find a way to escape the dollar sign within the sed command in a bash script. I have found here tons of answers that say that you need to put four backslashes in a row in order to escape the sign. I have also tried the version with two backslashes, but for some reason, I can't get it to work. Can someone please tell me what I'm doing wrong?
Let's say that you have a file called aaa.txt located in /home/Documents. The file has just only one line of text, which says aaa. I am trying to replace it using this command (please don't tell me that I can reference it in a different way than with line numbers because this is just a reduced example of something else I am doing):
sed -i "1ccd /home/userr/$PARAMETER/$METHOD" "/home/userr/Documents/aaa.txt"
The output that I get is this:
cd /home/userr/\/\
Which is not what I want. I want to have exactly this output, with dollar signs in the string:
cd /home/userr/$PARAMETER/$METHOD
What is the proper form of the string passed to the sed command to achieve this?
You can escape the dollar sign with a backslash:
sed -i "1ccd /home/userr/\$PARAMETER/\$METHOD" "/home/userr/Documents/aaa.txt"
Documentation here: https://www.gnu.org/software/bash/manual/html_node/Escape-Character.html
You need to remove the double quotes so sed will not try and expand it. This sed should work without escaping needed.
$ sed -i '1ccd /home/userr/$PARAMETER/$METHOD' /home/userr/Documents/aaa.txt

how to escape file path in bash script variable

I would like to escape a file path that is stored in a variable in a bash script.
I read several threads about escaping back ticks or but it seems not working as it should:
I have this variable:
The variables value is entered during the bash script execution as user parameter
CONFIG="/home/teams/blabla/blabla.yaml"
I would need to change this to: \/home\/teams\/blabla\/blabla.yaml
How can I do that with in the script via sed or so (not manually)?
With GNU bash and its Parameter Expansion:
echo "${CONFIG//\//\\/}"
Output:
\/home\/teams\/blabla\/blabla.yaml
Using the solution from this question, in your case it will look like this:
CONFIG=$(echo "/home/teams/blabla/blabla.yaml" | sed -e 's/[]\/$*.^[]/\\&/g')
echo "/home/teams/blabla/blabla.yaml" | sed 's/\//\\\//g'
\/home\/teams\/blabla\/blabla.yaml
explanation:
backslash is used to set the following letter/symbol as an regular expression or vice versa. double backslash is used when you need a backslash as letter.
Why does that need escaping? Is this an XY Problem?
If the issue is that you are trying to use that variable in a substitution regex, then the examples given should work, but you might benefit by removing some of the "leaning toothpick syndrom", which many tools can do just by using a different match delimiter. sed, for example:
$: sed "s,SOME_PLACEHOLDER_VALUE,$CONFIG," <<< SOME_PLACEHOLDER_VALUE
/home/teams/blabla/blabla.yaml
Be very careful about this, though. Commas are perfectly valid characters in a filename, as are almost anything but NULLs. Know your data.

Replace string within a file from a bash script

I need to replace within a little bash script a string inside a file but... I am getting weird results.
Let's say I want to replace:
<tag><![CDATA[text]]></tag>
With:
<tag><![CDATA[replaced_text]]></tag>
Should I use sed? I think due to / and [ ] I am getting weird results...
What would be the best way of approaching this?
Perl with -p option works almost as sed and it has \Q (quote) switch for its regexes:
perl -pe 's{\Q<tag><![CDATA[text]]></tag>}
{<tag><![CDATA[replaced_text]]></tag>}' YOUR_FILE
And in Perl you can use different punctuation to delimiter your expressions (s{...}{...} in my example).
Yes, you need to escape the brackets, and either escape slashes or use different delimiters.
sed 's,<tag><!\[CDATA\[text\]\]></tag>,<tag><!\[CDATA\[replaced)text\]\]></tag>,'
That said, SGML and XML are not actually any better than HTML when it comes to using regexes; don't expect this to generalize.
This should be enough:
$ echo '<tag><![CDATA[text]]></tag>' | sed 's/\[text\]/\[replaced_text\]/'
<tag><![CDATA[replaced_text]]></tag>
You can also change your / separator inside sed to a different character like ,, | or %.
Just use a delimiter other than /, here I use #:
sed -i 's#<tag><!\[CDATA\[text\]\]></tag>#<tag><![CDATA[replaced_text]]></tag>#g' filename
-i to have sed change the file instead of printing it out.
g is for matching more than once (global).
But do you know the exact string you want to match, both the tag and the text?
For instance, if you want to replace the text in all with your replaced_text:
perl -i -pe 's#(<tag><!\[CDATA\[)(.*?)(\]\]></tag>)#\1replaced_text\3#g' filename
Switched to perl because sed doesn't support non-greedy multipliers (the *?).

Replace a phrase in a file with a string which contains special Characters

I am using sed -e "s/foo/$bar/" -e "s/some/$text/" file.whatever to replace a phrase in a certain file. The problem is that the $bar string contains multiple special characters like /. So when I try to replace something in a text file using the following code...
#!/bin/bash
bar="http://stackoverflow.com/"
sed -e "s/foo/$bar/" -e "s/some/$text/ file.whatever
...then I get an error saying : sed: unknown option to s is there anything I can do about it?
You can use any delimiter. s#some#SOME# for example. Another good delimiter is vertical-bar. Other chars can work but have special significance for some contexts such as regular expressions.
You can get this difficulty in sed regardless of what delimiters you use, especially if you don't know what the string contains. I'd pick a different method for passing the shell variables into the helper interpreter.
awk -v rep1="$bar" -v rep2="$text" '{sub(/foo/, rep1); sub(/some/, rep2); print}'
or
perl -spe 's/foo/$rep1/; s/some/$rep2/' -- -rep1="$bar" -rep2="$text"
Correctness trumps brevity in this case.
(reference for Perl example)

Getting sed to Replace Text With Argument

Alright, I know this is a simple question, but I can't seem to get this sed command to work. I'm trying to get a text file and replace one bit of it from placeholder text to a study code. The study code that it is going to replace it with is passed into the script using arguments when the script is first ran. The problem is, when I try to replace the placeholder text with the variable $study, it replaces it with a literally "$study".
Right now my arguments set like this:
export study=$1
export tag=$2
export mode=$3
export select=$4
My sed command looks like this:
sed -i.backup -e 's/thisisthestudycodereplacethiswiththestudycode/$study/' freq.spx
Is there some easy way of getting sed to not look at the literal $study, or would it be better at this point to do it another way?
Use double quotes instead of single quotes.
Because ' quoting prevents shell variable expansions, and " quoting does not.
You probably won't run into this issue, but just in case...
Paul's answer is slightly suboptimal if $study might contain slashes or other characters with special meaning to sed.
mv freq.spx freq.spx.backup && \
awk -v "study=$study" '{
gsub(/thisisthestudycodereplacethiswiththestudycode/, study);
print;
}' freq.spx.backup > freq.spx
Although awkward (hah, pun!), this will always work regardless of $study's contents.
try this...................
sed -e 's/%d/'$a'/g' amar.htm , amar.htm having the string "%d" which is indeed to be replaced and "a" is having the string to replace.

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