I'm trying to replace instances of {$pear_root} in a config file with the $PEAR_ROOT variable in a shell script.
Using the method from here under "A Note About Bash Escape Character" I have:
ESC_PEAR_ROOT="${PEAR_ROOT//\//\\/}"
sed -i "s/{\$pear_root}/${ESC_PEAR_ROOT}/"../.serverconfig/test.txt
I'm getting back 34: Bad substitution which I think may mean that this is unsupported.
The problem seems to be the use of s/find/replace/, as I get the same error whether doing this with sed or with perl.
What is the simplest way to do this:
APP_ROOT=$(php ./scripts/get_realpath.php '../')
PEAR_ROOT="$APP_ROOT/pear"
ESC_PEAR_ROOT="${PEAR_ROOT//\//\\/}"
sed -e "s/{\$pear_root}/${ESC_PEAR_ROOT}/"../.serverconfig/test.txt
And end up with all instances of {$pear_root} in test.txt replaced with the path from PEAR_ROOT?
I'm not attached to this method - anything reliable will do.
This is a bit silly, but I notice you're missing a space between the end of your expression and the name of the file to which you wish to apply it.
/tmp $ sed -e 's/{$pear_root}/'"$PATH"'/' test
/tmp $ sed -e 's/{$pear_root}/'"$PATH"'/'test
sed: bad option in substitution expression
Ok, solved it.
The problem was:
This:
ESC_PEAR_ROOT="${PEAR_ROOT//\//\\/}"
Should have been this:
ESC_PEAR_ROOT="{PEAR_ROOT//\//\\/}"
That was what was causing my "bad substitution" error.
Also, realized I didn't need to escape, since I could just use a different delimiter to s, so I don't even need that line.
Final result ended up as:
APP_ROOT=$(php ./scripts/get_realpath.php '../')
PEAR_ROOT="$APP_ROOT/pear"
sed -i "s#{\$pear_root}#${PEAR_ROOT}#g" ../.serverconfig/test.txt
Related
This question already has answers here:
Replace whole line when match found with sed
(4 answers)
Closed 4 years ago.
How do I find line starts with and replace complete line?
File output:
xyz
abc
/dev/linux-test1/
Code:
output=/dev/sda/windows
sed 's/^/dev/linux*/$output/g' file.txt
I am getting below Error:
sed: -e expression #1, char 9: unknown option to `s'
File Output expected after replacement:
xyz
abc
/dev/sda/windows
Let's take this in small steps.
First we try changing "dev" to "other":
sed 's/dev/other/' file.txt
/other/linux-test1/
(Omitting the other lines.) So far, so good. Now "/dev/" => "/other/":
sed 's//dev///other//' file.txt
sed: 1: "s//dev///other//": bad flag in substitute command: '/'
Ah, it's confused, we're using '/' as both a command delimiter and literal text. So we use a different delimiter, like '|':
sed 's|/dev/|/other/|' file.txt
/other/linux-test1/
Good. Now we try to replace the whole line:
sed 's|^/dev/linux*|/other/|' file.txt
/other/-test1/
It didn't replace the whole line... Ah, in sed, '*' means the previous character repeated any number of times. So we precede it with '.', which means any character:
sed 's|^/dev/linux.*|/other/|' file.txt
/other/
Now to introduce the variable:
sed 's|^/dev/linux.*|$output|' file.txt
$output
The shell didn't expand the variable, because of the single quotes. We change to double quotes:
sed "s|^/dev/linux.*|$output|" file.txt
/dev/sda/windows
This might work for you (GNU sed):
output="/dev/sda/windows"; sed -i '\#/dev/linux.*/#c'"$output" file
Set the shell variable and change the line addressed by /dev/linux.*/ to it.
N.B. The shell variable needs to interpolated hence the ; i.e. the variable may be set on a line on its own. Also the the delimiter for the sed address must be changed so as not to interfere with the address, hence \#...#, and finally the shell variable should be enclosed in double quotes to allow full interpolation.
I'd recommend not doing it this way. Here's why.
Sed is not a programming language. It's a stream editor with some constructs that look and behave like a language, but it offers very little in the way of arbitrary string manipulation, format control, etc.
Sed only takes data from a file or stdin (also a file). Embedding strings within your sed script is asking for errors -- constructs like s/re/$output/ are destined to fail at some point, almost regardless of what workarounds you build into your sed script. The best solutions for making sed commands like this work is to do your input sanitization OUTSIDE of sed.
Which brings me to ... this may be the wrong tool for this job, or might be only one component of the toolset for the job.
The error you're getting is obviously because the sed command you're using is horribly busted. The substitute command is:
s/pattern/replacement/flags
but the command you're running is:
s/^/dev/linux*/$output/g
The pattern you're searching for is ^, the null at the beginning of the line. Your replacement pattern is dev, then you have a bunch of text that might be interpreted as flags. This plainly doesn't work, when your search string contains the same character that you're using as a delimiter to the options for the substitute command.
In regular expressions and in sed, you can escape things. You while you might get some traction with s/^\/dev\/linux.*/$output/, you'd still run into difficulty if $output contained slashes. If you're feeding this script to sed from bash, you could use ${output//\//\\\/}, but you can't handle those escapes within sed itself. Sed has no variables.
In a proper programming language, you'd have better separation of variable content and the commands used for the substitution.
output="/dev/sda/windows"
awk -v output="$output" '$1~/\/dev\/linux/ { $0=output } 1' file.txt
Note that I've used $1 here because in your question, your input lines (and output) appear to have a space at the beginning of each line. Awk automatically trims leading and trailing space when assigning field (positional) variables.
Or you could even do this in pure bash, using no external tools:
output="/dev/sda/windows"
while read -r line; do
[[ "$line" =~ ^/dev/linux ]] && line="$output"
printf '%s\n' "$line"
done < file.txt
This one isn't resilient in the face of leading whitespace. Salt to taste.
So .. yes, you can do this with sed. But the way commands get put together in sed makes something like this risky, and despite the available workarounds like switching your substitution command delimiter to another character, you'd almost certainly be better off using other tools.
I have two sed command which includes in my cook.sh script. One command is
sed -E -i "s/^(\\\$mainDomain=\")[^\"]+(\";)$/\1$MainDomain\2/" /var/config.php
This is working fine.
But the below command which is almost same. But it is not working.
sed -E -i "s/^(\\\$authURI=\")[^\"]+(\";)$/\1$duo_auth\2/" /var/config.php
That give the below error message
sed: -e expression #1, char 36: unknown option to `s'
Any idea on this ?
The issue is likely due to your replacement variable $duo_auth having a un-escaped /, change the default sed separator from / to ~ as
sed -E -i "s~^(\\\$authURI=\")[^\"]+(\";)$~\1$duo_auth\2~" /var/config.php
Try it without -i for seeing if the replacement is as expected and put it back after confirmation.
Example:-
cat /var/config.php
<?php
$authURI="dev.digin.io";
now setting the variable
duo_auth="http://auth.uri.digin.io:3048/"
Now the replacement, without -i
sed -E "s~^(\\\$authURI=\")[^\"]+(\";)$~\1$duo_auth\2~" /var/config.php
<?php
$authURI="http://auth.uri.digin.io:3048/";
The problem is probably due to $duo_auth containing an unescaped /. This means that the sed editing script will have a syntax error.
You may pick any other character to use as a delimiter in the s/.../.../ command, for example #:
sed "s#....#....#"
Just make sure that you pick a character that is not ever going to turn up in either $duo_auth or $authURI.
While testing, I'd recommend that you avoid using in-place-editing (-i) with sed. Also, the -i switch is horribly non-portable between sed implementations (some requires an argument).
Instead, do the slightly more cumbersome
sed -e "s#...#...#" data.in >data.in.tmp && mv -f data.in.tmp data.in
While testing, check the data.in.tmp file before moving it.
I am trying to replace a sed command with a sed command and it keeps falling over so after a few hours of "picket fencing" I thought I would ask the question here.
I have various bash scripts that contain this kind of line:
sed 's/a hard coded server name servername.//'
I would like to replace it with:
sed "s/a hard coded server name $(hostname).//"
Note the addition of double quotes so that the $(hostname) is expanded which make this a little trickier than I expected.
So this was my first of many failed attempts:
cat file | sed 's!sed \'s\/a hard coded server name servername.\/\/\'!sed \"s\/a hard coded server name $(hostname).\/\/\"!g'
I also tried using sed's nice "-e" option to break down the replace into parts to try and target the problem areas. I wouldn't use the "-e" switch in a solution but it is useful sometimes for debugging:
cat file | sed -e 's!servername!\$\(hostname\)!' -e 's!\| sed \'s!\| sed \"s!'
The first sed works as expected (nothing fancy happening here) and the second fails so no point adding the third that would have to replace the closing double quote.
At this point my history descends into chaos so no point adding any more failed attempts.
I wanted to use the first replacement in a single command as the script is full of sed commands and I wanted to target just one specific command in the script.
Any ideas would be appreciated.
Here's how you could do it in awk if you ignore (or handle) metachars in the old and new text like you would with sed:
$ awk -v old="sed 's/a hard coded server name servername.//'" \
-v new="sed 's/a hard coded server name '\"\$(hostname)\"'.//' \
'{sub(old,new)}1' file
sed 's/a hard coded server name '"$(hostname)"'.//'
or to avoid having to deal with metachars, use only strings for the comparison and replacement:
$ awk -v old="sed 's/a hard coded server name servername.//'" \
-v new="sed 's/a hard coded server name '\"\$(hostname)\"'.//'" \
's=index($0,old){$0=substr($0,1,s-1) new substr($0,s+length(old))}1' file
sed 's/a hard coded server name '"$(hostname)"'.//'
Follow the behavior of templating tools by using a sequence that should never appear in actual use and replace that. For example, using colons simply because they require less quoting:
#!/bin/bash
sed "s/:servername:/$(hostname)/g" <<EOF > my_new_script.bash
echo "This is :servername:"
EOF
I've used echo in the internal script for purposes of clarity. You could have equally used something like:
sed 's/complex substitution :servername:/inside quotes :servername:/'
which avoids quoting hassles because the outer sed is treating the here document as plain text.
We have couple of scripts where we want to replace variable evaluation method from $VAR_NAME to ${VAR_NAME}
This is required so that scripts will have uniform method for variable evaluation
I am thinking of using sed for the same, I wrote sample command which looks like follows,
echo "\$VAR_NAME" | sed 's/^$[_a-zA-Z0-9]*/${&}/g'
output for the same is
${$VAR_NAME}
Now i don't want $ inside {}, how can i remove it?
Any better suggestions for accomplishing this task?
EDIT
Following command works
echo "\$VAR_NAME" | sed -r 's/\$([_a-zA-Z]+)/${\1}/g'
EDIT1
I used following command to do replacement in script file
sed -i -r 's:\$([_a-zA-Z0-9]+):${\1}:g' <ScriptName>
Since the first part of your sed command searches for the $ and VAR_NAME, the whole $VAR_NAME part will be put inside the ${} wrapper.
You could search for the $ part with a lookbehind in your regular expression, so that you end up ending the sed call with /{&}/g as the $ will be to the left of your matched expression.
http://www.regular-expressions.info/lookaround.html
http://www.perlmonks.org/?node_id=518444
I don't think sed supports this kind of regular expression, but you can make a command that begins perl -pe instead. I believe the following perl command may do what you want.
perl -p -e 's/(?<=\$)[_a-zA-Z0-9]*/{$&}/g'
PCRE Regex to SED
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.