I am struggling with a conversion of a data file to csv when there is punctuation in the title field.
I have a bash script that obtains the file and processes it, and it almost works. What gets me is when there are commas in a free text title field, which then create extra fields.
I have tried some sed examples to replace between patterns but I have not gotten any of them to work. What I want to do is work between two patterns and replace commas with either nothing or perhaps a semicolon.
Taking this string:
name:A100040,title:Oatmeal is better with raisins, dates, and sugar,current_balance:50000,
Replacing with this:
name:A100040,title:Oatmeal is better with raisins dates and sugar,current_balance:50000,
I should probably use "title:" and ",current_" to denote the start and end of the block where I want to make the change to avoid situations like this:
name:A100040,title:Re-title current periodicals, recent books,current_balance:50000,
So far I have not gotten the substitution to match. In this case I am using !! to make the change obvious:
teststring="name:A100040,title:Oatmeal is better with raisins, dates, and sugar,current_balance:50000,"
echo $teststring |sed '/title:/,/current_/s/,/!!/g'
name:A100040!!title:Oatmeal is better with raisins!! dates!! and sugar!!current_balance:50000!!
Any help appreciated.
This is one way which could undoubtedly be refined:
perl -ple 'm/(.*?)(title:.*?)(current_balance:.*)/; $save = $part = $2; $part =~ s/,/!!/g; s/$save/$part/'
First, using sed or awk to parse CSV is almost always the wrong thing to do, because they do not allow field delimiters to be quoted. That said, it seems like a better approach would be to quote the fields so that your output would be:
name:"A100040",title:"Oatmeal ... , dates, and sugar",current_balance:50000
Using sed you can try: (this is fragile)
sed 's/:\([^:]*\),\([^,:]*\)/:"\1",\2/g'
If you insist on trying to parse the csv with "standard" tools and you consider perl to be standard, you could try:
perl -pe '1 while s/,([^,:]*),/ $1,/g'
Related
So I think I've cracked the regex but just can't crack how to get sed to make the changes. I have a variable which is this:
MAKEVAR = EPICS_BASE=$CI_PROJECT_DIR/3.16/base IPAC=$CI_PROJECT_DIR/3.16/support/ipac SNCSEQ=$CI_PROJECT_DIR/3.16/support/seq
(All one line). But I want to delete the particular section defining IPAC so my regex looks like this:
(IPAC.+\s)
I know from using this tool that that should be correct:
https://www.regextester.com/98103
However when I run different iterations of trying out sed like:
sed 's/(IPAC.+\s)/\&/g' <<< "$MAKEVAR"
And then echo out MAKEVAR, the IPAC section still exists.
How can I update a particular section of text in a shell variable to remove a section beginning with IPAC up until the next space?
Thanks in advance
regextester (or any other online tool) is a great way to verify that a regexp works in that online tool. Unfortunately that doesn't mean it'll work in any given command-line tool. In particular your regexp includes \s which is specific to PCREs and some GNU tools, and uses (...) to delineate capture groups but that's only used in EREs and PCREs, not BREs such as sed supports by default where you'd have to use \(...\), and your replacement text is using '&' which is telling sed you want to replace the string that matches the regexp with a literal \& when in fact you just want to remove it.
This is how to do what I think you're trying to do using any sed:
$ sed 's/IPAC[^ ]* //' <<< "$MAKEVAR"
EPICS_BASE=$CI_PROJECT_DIR/3.16/base SNCSEQ=$CI_PROJECT_DIR/3.16/support/seq
Nevermind, found a workaround:
MAKEVAR=$(sed -E 's/(IPAC.+ipac)//' <<<"$MAKEVAR")
Use a shorter
MAKEVAR=$(sed 's/IPAC.*ipac//' <<< "$MAKEVAR")
IPAC.*ipac matches all the way from first IPAC to last ipac. The matched text is removed from the text.
I did check the ABS, but it was hard to find a reference to my problem/question there.
Here it is. Consider the following code (Which extracts the first character of OtherVar and then converts MyVar to uppercase):
OtherVar=foobar
MyChar=${OtherVar:0:1} # get first character of OtherVar string variable
MyChar=${MyChar^} # first character to upper case
Could I somehow condense the second and third line into one statement?
P.S.: As was pointed out below, not needs to have a named variable. I should add, I would like to not add any sub-shells or so and would also accept a somehow hacky way to achieve the desired result.
P.P.S.: The question is purely educational.
You could do it all-in-one without forking sub-shell or running external command:
printf -v MyChar %1s "${OtherVar^}"
Or:
read -n1 MyChar <<<"${OtherVar^}"
Another option:
declare -u MyChar=${OtherVar:0:1}
But I can't see the point in such optimization in a bash script.
There are more suitable text processing interpreters, like awk, sed, even perl or python if performance matters.
You could use the cut command and put it in a complex expression to get it on one line, but I'm not sure it makes the code too much clearer:
OtherVar=foobar
MyChar=$(echo ${OtherVar^} | cut -c1-1) # uppercase first character and cut string
I'm trying to extract a tag value of an HTML node that I already have in a variable.
I'm currently using Zsh but I'm trying to make it work in Bash as well.
The current variable has the value:
<span class="alter" fill="#ffedf0" data-count="0" data-more="none"/>
and I would like to get the value of data-count (in this case 0, but could be any length integer).
I have tried using cut, sed and the variables expansion as explained in this question but I haven't managed to adapt the regexs, or maybe it has to be done differently for Zsh.
There is no reason why sed would not work in this situation. For your specific case, I would do something like this:
sed 's/.*data-count="\([0-9]*\)".*/\1/g' file_name.txt
Basically, it just states that sed is looking for the a pattern that contains data-count=, then saves everything within the paranthesis \(...\) into \1, which is subsequently printed in place of the match (full line due to the .*)
Could you please try following.
awk 'match($0,/data-count=[^ ]*/){print substr($0,RSTART+12,RLENGTH-13)}' Input_file
Explanation: Using match function of awk to match regex data-count=[^ ]* means match everything from data-count till a space comes, if this regex is TRUE(a match is found) then out of the box variables RSTART and RLENGTH will be set. Later I am printing current line's sub-string as per these variables values to get only value of data-count.
With sed could you please try following.
sed 's/.*data-count=\"\([^"]*\).*/\1/' Input_file
Explanation: Using sed's capability of group referencing and saving regex value in first group after data-count=\" which is its length, then since using s(substitution) with sed so mentioning 1 will replace all with \1(which is matched regex value in temporary memory, group referencing).
As was said before, to be on the safe side and handle any syntactically valid HTML tag, a parser would be strongly advised. But if you know in advance, what the general format of your HTML element will look like, the following hack might come handy:
Assume that your variable is called "html"
html='<span class="alter" fill="#ffedf0" data-count="0" data-more="none"/>'
First adapt it a bit:
htmlx="tag ${html%??}"
This will add the string tag in front and remove the final />
Now make an associative array:
declare -A fields
fields=( ${=$(tr = ' ' <<<$htmlx)} )
The tr turns the equal sign into a space and the ${= handles word splitting. You can now access the values of your attributes by, say,
echo $fields[data-count]
Note that this still has the surrounding double quotes. Yuo can easily remove them by
echo ${${fields[data-count]%?}#?}
Of course, once you do this hack, you have access to all attributes in the same way.
I'm trying to make a script that will go into a directory and run my own application with each file matching a regular expression, specifically Test[0-9]*.txt.
My input filenames look like this TestXX.txt. Now, I could just use cut and chop off the Test and .txt, but how would I do this if XX wasn't predefined to be two digits? What would I do if I had Test1.txt, ..., Test10.txt? In other words, How would I get the [0-9]* part?
Just so you know, I want to be able to make a OutputXX.txt :)
EDIT:
I have files with filename Test[0-9]*.txt and I want to manipulate the string into Output[0-9]*.txt
Would something like this help?
#!/bin/bash
for f in Test*.txt ;
do
process < $f > ${f/Test/Output}
done
Bash Shell Parameter Expansion
A good tutorial on regexes in bash is here. Summarizing, you need something like:
if [[$filenamein =~ "^Test([0-9]*).txt$"]]; then
filenameout = "Output${BASH_REMATCH[1]}.txt"
and so on. The key is that, when you perform the =~" regex-match, the "sub-matches" to parentheses-enclosed groups in the RE are set in the entries of arrayBASH_REMATCH(the[0]entry is the whole match,1` the first parentheses-enclosed group, etc).
You need to use rounded brackets around the part you want to keep.
i.e. "Test([0-9]*).txt"
The syntax for replacing these bracketed groups varies between programs, but you'll probably find you can use \1 , something like this:
s/Test(0-9*).txt/Output\1.txt/
If you're using a unix shell, then 'sed' might be your best bet for performing the transformation.
http://www.grymoire.com/Unix/Sed.html#uh-4
Hope that helps
for file in Test[0-9]*.txt;
do
num=${file//[^0-9]/}
process $file > "Output${num}.txt"
done
I am writing a shell (bash) script and I'm trying to figure out an easy way to accomplish a simple task.
I have some string in a variable.
I don't know if this is relevant, but it can contain spaces, newlines, because actually this string is the content of a whole text file.
I want to replace the last occurence of a certain substring with something else.
Perhaps I could use a regexp for that, but there are two moments that confuse me:
I need to match from the end, not from the start
the substring that I want to scan for is fixed, not variable.
for truncating at the start: ${var#pattern}
truncating at the end ${var%pattern}
${var/pattern/repl} for general replacement
the patterns are 'filename' style expansion, and the last one can be prefixed with # or % to match only at the start or end (respectively)
it's all in the (long) bash manpage. check the "Parameter Expansion" chapter.
amn expression like this
s/match string here$/new string/
should do the trick - s is for sustitute, / break up the command, and the $ is the end of line marker. You can try this in vi to see if it does what you need.
I would look up the man pages for awk or sed.
Javier's answer is shell specific and won't work in all shells.
The sed answers that MrTelly and epochwolf alluded to are incomplete and should look something like this:
MyString="stuff ttto be edittted"
NewString=`echo $MyString | sed -e 's/\(.*\)ttt\(.*\)/\1xxx\2/'`
The reason this works without having to use the $ to mark the end is that the first '.*' is greedy and will attempt to gather up as much as possible while allowing the rest of the regular expression to be true.
This sed command should work fine in any shell context used.
Usually when I get stuck with Sed I use this page,
http://sed.sourceforge.net/sed1line.txt