I have a script that I am writing that checks a value and then based on the value modifies it.
I am trying to understand why it works this one way and not the other. Based on the google and stackoverflow searches I did, nothing really fits what I am trying to understand.
The value it is trying to change is test_value = 5 and changes the 5 to a 6. In the file there are two like lines.
test_value = 5
test_value_action = log
Script content is below:
#!/bin/bash
CHECK="test_value"
sed -i 's|^\("$CHECK" = \).*|\1'6'|' /user/file.txt
That doesn't work. But if I hard code the value for check it works
#!/bin/bash
CHECK="test_value"
sed -i 's|^\(test_value = \).*|\1'6'|' /user/file.txt
What am I failing to understand? Also for other ones I have wrote where there is only one single line in the file that it can match, it works with $CHECK.
Your variable is still within single quote hence not getting expanded. Use:
sed -i 's|^\('"$CHECK"' = \)*.|\1'6'|' /user/file.txt
Related
I have a script that contains 2 variables. One of the variables is a directory path and the other is a user input variable. Once the user enters the variable, in this case a certificate name, I use sed to replace the text of xxxxx with both the script_path separated by a / and the the certfile variable.
Still new at programming but I've managed to get my script working aside from the issue below. I've tried escaping the variables the "/" and nothing seems to work.
I've also tried changing the delimiter that sed uses as well with no luck. I did search around quite a bit and didn't find anything specific with using a "/" and concatenating variables so apologies up front if this has already been solved.
#!/bin/bash
script_path=/opt/ceflog
read -p 'Enter the name of the certificate file: ' certfile
sed -e "s/pkcs12_file = xxxxxx/pkcs12_file = $script_path/$certfile/g" \$script_path/cef.conf
What is should look like is something like the below.
pkcs12_file = /opt/ceflog/192.168.1.1_1.pkcs12
As always thanks in advance for you help.
I guess you want to do something like this
$ path='/opt/ceflog'; cert='192.168.1.1_1.pkcs12';
$ echo pkcs12_file = xxxxxx/pkcs12_file |
sed -E 's~(pkcs12_file =) (xxxxxx/pkcs12_file)~\1 '"${path}/${cert}"'~'
pkcs12_file = /opt/ceflog/192.168.1.1_1.pkcs12
use a different sed delimiter (here I picked ~) than the default one (/), since you may have it in your data.
So looks like there were 2 issues. I escaped the use of the variables on the end "\$script_path/cef.conf" and changing the dilemeter for sed I was able to get it to work.
sed -e "s|pkcs12_file = xxxxxx|pkcs12_file = $script_path/$certfile|g" $script_path/cef.conf
Thanks again all.
Before to write, of course I read many other similar cases. Example I used #!/bin/bash instead of #!/bin/sh
I have a very simple script that reads lines from a template file and wants to replace some keywords with real data. Example the string <NAME> will be replaced with a real name. In the example I want to replace it with the word Giuseppe. I tried 2 solutions but they don't work.
#!/bin/bash
#read the template and change variable information
while read LINE
do
sed 'LINE/<NAME>/Giuseppe' #error: sed: -e expression #1, char 2: extra characters after command
${LINE/<NAME>/Giuseppe} #error: WORD(*) command not found
done < template_mail.txt
(*) WORD is the first word found in the line
I am sorry if the question is too basic, but I cannot see the error and the error message is not helping.
EDIT1:
The input file should not be changed, i want to use it for every mail. Every time i read it, i will change with a different name according to the receiver.
EDIT2:
Thanks your answers i am closer to the solution. My example was a simplified case, but i want to change also other data. I want to do multiple substitutions to the same string, but BASH allows me only to make one substitution. In all programming languages i used, i was able to substitute from a string, but BASH makes this very difficult for me. The following lines don't work:
CUSTOM_MAIL=$(sed 's/<NAME>/Giuseppe/' template_mail.txt) # from file it's ok
CUSTOM_MAIL=$(sed 's/<VALUE>/30/' CUSTOM_MAIL) # from variable doesn't work
I want to modify CUSTOM_MAIL a few times in order to include a few real informations.
CUSTOM_MAIL=$(sed 's/<VALUE1>/value1/' template_mail.txt)
${CUSTOM_MAIL/'<VALUE2>'/'value2'}
${CUSTOM_MAIL/'<VALUE3>'/'value3'}
${CUSTOM_MAIL/'<VALUE4>'/'value4'}
What's the way?
No need to do the loop manually. sed command itself runs the expression on each line of provided file:
sed 's/<NAME>/Giuseppe/' template_mail.txt > output_file.txt
You might need g modifier if there are more appearances of the <NAME> string on one line: s/<NAME>/Giuseppe/g
A config file that the last line contains data that I want to assign everything to the RIGHT of the = sign into a variable that I can display and call later in the script.
Example: /path/to/magic.conf:
foo
bar
ThisOption=foo.bar.address:location.555
What would be the best method in a bash shell script to read the last line of the file and assign everything to the right of the equal sign? In this case, foo.bar.address:location.555.
The last line always has what I want to target and there will only ever be a single = sign in the file that happens to be the last line.
Google and searching here yielded many close but non-relative results with using sed/awk but I couldn't come up with exactly what I'm looking for.
Use sed:
variable=$(sed -n 's/^ThisOption=//p' /path/to/magic.conf)
echo "The option is: $variable")
This works by finding and removing the ThisOption= marker at the start of the line, and printing the result.
IMPORTANT: This method absolutely requires that the file be trusted 100%. As mentioned in the comments, anytime you "eval" code without any sanitization there are grave risks (a la "rm -rf /" magnitude - don't run that...)
Pure, simple bash. (well...using the tail utility :-) )
The advantage of this method, is that it only requires you to know that it will be the last line of the file, it does not require you to know any information about that line (such as what the variable to the left of the = sign will be - information that you'd need in order to use the sed option)
assignment_line=$(tail -n 1 /path/to/magic.conf)
eval ${assignment_line}
var_name=${assignment_line%%=*}
var_to_give_that_value=${!var_name}
Of course, if the var that you want to have the value is the one that is listed on the left side of the "=" in the file then you can skip the last assignment and just use "${!var_name}" wherever you need it.
Apologies for a seemingly inane question. But I have spent the whole day trying to figure it out and it drives me up the walls. I'm trying to write a seemingly simple bash script that would take a list of files in the directory from ls, replace part of the file names using sed, get unique names from the list and pass them onto some command. Like so:
inputs=`ls *.ext`
echo $inputs
test1_R1.ext test1_R2.ext test2_R1.ext test2_R2.ext
Now I would like to put it through sed to replace 1.ext and 2.ext with * to get test1_R* etc. Then I'd like to remove resulting duplicates by running sort -u to arrive to the following $outputs variable:
echo $outputs
test1_R* test2_R*
And pass this onto a command, like so
cat $outputs
I can do something like this in a command line:
ls *.ext | sed s/..ext/\*/g | sort -u
But if I try to assign the above to a variable in the script it just returns the output from the ls. I have tried several ways to do it: including the whole pipe in the script. Running each command separately and assigning it to a variable, then passing that variable to the next command and writing the outputs to files then passing the file to the next command. But so far none of this managed to achieve what I aimed to. I think my problem lies in (except general cluelessness aroung bash scripting) inability to run seq on a variable within script. There seems to be a lot of advice around in how to pass variables to pattern or replacement string in sed, but they all seem to take files as input. But I understand that it might not be the proper way of doing it anyway. Therefore I would really appreciate if someone could suggest an elegant way to achieve, what I'm trying to.
Many thanks!
Update 2/06/2014
Hi Barmar, thanks for your answer. Can't say it solved the problem, but it helped pin-pointing it. Seems like the problem is in me using the asterisk. I have to say, I'm very puzzled. The actual file names I've got are:
test1_R1.fastq.gz test1_R2.fastq.gz test2_R1.fastq.gz test2_R2.fastq.gz
If I'm using the code you suggested, which seems to me the right way do to it:
ins=$(ls *.fastq.gz | sed 's/..fastq.gz/\*/g' | sort -u)
Sed doesn't seem to do anything and I'm getting the output of ls:
test1_R1.fastq.gz test1_R2.fastq.gz test2_R1.fastq.gz test2_R2.fastq.gz
Now if I replace that backslash with anything else, the sed works, but it also returns whatever character I'm putting in front (or after) the asteriks:
ins=$(ls *.fastq.gz | sed 's/..fastq.gz/"*/g' | sort -u)
test1_R"* test2_R"*
That's odd enough, but surely I can just put an "R" in front of the asteriks and then replace R in the search pattern string, right? Wrong! If I do that whichever way: 's/R..fastq.gz/R*/g' 's/...fastq.gz/R*/g' 's/[A-Z]..fastq.gz/R*/g' I'm back to the original names! And even if I end up with something like test1_RR* test2_RR* and try to run it through sed again and replace "_R" for "_" or "RR" for "R", I'm having no luck and I'm back to the original names. And yet I can replace the rest of the file name no problem, just not to get me test1_R* I need.
I have a feeling I should be escaping that * in some very clever way, but nothing I've tried seems to work. Thanks again for your help!
This is how you capture the result of the whole pipeline in a variable:
var=$(ls *.ext | sed s/..ext/\*/g | sort -u)
Looking for help creating a script that will replace the last line of an XML file with a tag. I have a few hundred files so I'm looking for something that will process them in a loop. I've managed to rename the files sequentially like this:
posts1.xml
posts2.xml
posts3.xml
etc...
to make it easier to loop through. But I have no idea how to write a script to do this. I'm open to using either Linux or Windows (but i would guess that Linux is better for this kind of task).
So if you want to append a line to every file:
sed -i '$a<YOUR_SHINY_NEW_TAG>' *xml
To replace the last line:
sed -i '$s/.*/<YOUR_SHINY_NEW_TAG>/' *xml
But do note, sed is not the ideal tool to modify xml.
XMLStarlet is a command-line toolkit for performing XML parsing and manipulations. Note that as an XML-aware toolkit, it'll respect XML structure, character encoding and entity substitution.
Check out the ed command to see how to modify documents. You can wrap this in a standard bash loop.
e.g. in a doc consisting of a chain of <elem>s, you can add a following <added>5</added>:
mkdir new
for x in *.xml; do
xmlstarlet ed -a "//elem[count(//elem)]" -t elem -n added -v 5 $x > new/$x
done
Linux way using sed:
To edit the last line of the file in place, you can use sed:
sed -i '$s_pattern_replacement_' filename
To change the whole line to "replacement" use $s_.*_replacement_. Be sure to escape any _'s in replacement with a \.
To loop over files, just use for:
for f in /path/posts*.xml; do sed -i '$s_.*_replacement_' $f; done
This, however, is a dirty way as it's not aware of the XML structure, whereas the XML structure is not affected by newlines. You have to be sure the last line of the files contains exactly what you expect it to.
It makes little to no difference whether you're on Linux, Windows or MacOS
The question is what language do you want to use?
The following is an example in c# (not optimized, but read it as speudocode):
string rootDirectory = #"c:\myfiles";
var files = Directory.GetFiles(rootDirectory, "*.xml");
foreach (var file in files)
{
var lines = File.ReadAllLines(file);
lines[lines.Length - 1] = "whatever you want here";
File.WriteAllLines(file, lines);
}
You can compile this and run it on Windows, Linux, etc..
Or you could do the same in Python.
Of course this method does not actually parse the XML,
but you just wanted to replace the last line right?