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sed find and replace between two tags with multi line
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I need to replace a token in a file with a multi-line paragrah, which has several line breakers inside it if the paragraph is represented as a string.
If I use sed the usually for a string to string replacement, the line breakers inside the new string would complain.
So now I want to open the file and seek to that token location, then write the new content into the file from there, but not sure how to achieve that. Can anybody help?
EDIT:
Looks like I probably can put both the file and the content to be inserted as arrays then use splice in perl. Might not be the easiest way though.
perl -i -pe's/token/foo\nbar\nbaz\n/g' file
You can't really insert into a file. Just like inserting into a string, you must first move the remainder of the string out of the way. With files, it's easier just to copy the entire file.
The provided code opens file, deletes file, creates file, then copies (with substitutions) from the open handle to the new handle.
It's my understanding that sed can do this too. It's my understanding that sed also uses -i to enable this feature.
Check out: How do I change, delete, or insert a line in a file, or append to the beginning of a file?
The easiest solutions will be to either use perl's $INPLACE_EDIT, optionally done as a one liner like demonstrated by ikegami, or perhaps to use Tie::File.
Related
I have been working on a product code to resolve an issue but am stuck on a line of code
Can anyone help me understand what exactly does this command do?
perl -MText::CSV -lne 'BEGIN{$p = Text::CSV->new()} print join "|", $p->fields() if $p->parse($_)' /home/daily/${FULL_FILENAME} > /home/output.txt
I think its to copy the file to my home location with some transformations but not sure exactly
This is a slightly broken program that translates a comma-separated values (CSV) file to a pipe-separated values file.
The particular command-line switches are documented in perlrun. This is a "one-liner", so you can read about those to see what's going on there.
The Text::CSV module deals with CSV files, and the program is parsing a line from the file and re-outputting as a pipe-separated file.
But, this program deals with each line as a complete record. That might be fine for you, but at some point you might end up with a literal value that has a newline in it, like a,"b\nc",d. Now reading line-by-line breaks the program since the quotes appear to be unclosed within the first line. Note only that, it blindly concatenates the parsed fields without considering if any of the fields should be quoted. It might be unlikely that a pipe character would be in the data, but the problem isn't it's rarity but the consequences and costliness when it does show up.
The rewrite.pl example script in the related module Text::CSV_XS is a tool that could replace this one-liner. It properly reads the input and knows how to properly translate it.
I have a large PDF (~20mb, 160 mb. uncompressed).
I need to do a find and replace in the text in it, about 1000 times.
Here is what I tried.
Via SVG
Tranform to SVG (inkscape)
Read SVG line by line and do the replace in the file
Transform back to PDF
=> bad output, probably due to some geometric transform matrix in the SVG, the text is not well rendered
Creating ~1000 sed command
Uncompress PDF
Perform each replace with a sed command
Recompress PDF
=> way too long. each sed command takes about 20 sec, leading to several hours of process
Read line-by-line and replace
Uncompress PDF
Read line by line the PDF
find text to be replaced
replace using perl
write line to a new file
Compress the new file
=> due to left data-stream in the uncompressed PDF, the new file is apparently damaged (writing binary as lines of text)
I wonder if it would be possible to read line-by-line the uncompressed PDF, but do the editing directly in it. How could I do this?
I have searched for perl inline editing, but it performs the changes in the whole file at once, while I'd like to edit a single line.
Other ideas are more than welcome ;)
Following advise, I used CAM::PDF, this was the most efficient and simple solution
There is no difference between 2. and 3. Sed reads the input file line by line and writes changed lines into the output file. If you fed -i switch to it, sed just opens the input file and then unlinks (it's what rm do) then opens the output file with the same name and writes into. That's it. No magic involved. So if you damaged content by Perl, but not by sed you do something different than by sed. The main difference is, you can make Perl script way faster for replacing many strings. See Using sed on text files with a csv
The main trick is you can compile regexp for search nad replace which works in linear time.
my %replace = ( foo => 'bar' );
my $re = join '|', map quotemeta, keys %replace;
$re = qr/($re)/;
while (<>) {
s/$re/$replace{$1}/g;
}
You can use it with your original approach, but I would recommend to make it in Perl script which allows you to keep the regexp and replace hash between pdf files. You can also try it to combine with CAM::PDF. There is the example script changepagestring.pl in it. You can also look at PDF::API2 which would require more work but may provide better result. But remember, PDF format is not intended for modification.
You can follow the pdftk steps as described in
How to find and replace text in a existing PDF file with PDFTK (or other command line application)
You can first split the PDF into smaller documents with a few pages each, replace the text and again merge them together - all using pdftk.
There is also the PDFEdit software (http://pdfedit.cz/en/index.html). It is a GUI app with a scripting interface. You can process individual pages and then do a find replace using scripting commands. See if it loads your PDF.
I am quite stuck; I need to compress the content of a folder, where I have multiple files (extension .dat). I went for shell scripting.
So far I told myself that is not that hard: I just need to recursively read the content of the dir, get the name of the file and zip it, using the name of the file itself.
This is what I wrote:
for i in *.dat; do zip $i".zip" $i; done
Now when I try it I get a weird behavior: each file is called like "12/23/2012 data102 test1.dat"; and when I run this sequence of commands; I see that zip instead of recognizing the whole file name, see each part of the string as single entity, causing the whole operation to fail.
I told myself that I was doing something wrong, and that the i variable was wrong; so I have replaced echo, instead than the zip command (to see which one was the output of the i variable); and the $i output is the full name of the file, not part of it.
I am totally clueless at this point about what is going on...if the variable i is read by zip it reads each single piece of the string, instead of the whole thing, while if I use echo to see the content of that variable it gets the correct output.
Do I have to pass the value of the filename to zip in a different way? Since it is the content of a variable passed as parameter I was assuming that it won't matter if the string is one or has spaces in it, and I can't find in the man page the answer (if there is any in there).
Anyone knows why do I get this behavior and how to fix it? Thanks!
You need to quote anything with spaces in it.
zip "$i.zip" "$i"
Generally speaking, any variable interpolation should have double quotes unless you specifically require the shell to split it into multiple tokens. The internal field separator $IFS defaults to space and tab, but you can change it to make the shell do word splitting on arbitrary separators. See any decent beginners' shell tutorial for a detailed account of the shell's quoting mechanisms.
I could not find this answer in the man or info pages, nor with a search here or on Google. I have a file which is, in essence, a text file, but it somehow got screwed up upon saving. (I think there are a few strange bytes at the front of the file accidentally.)
I am able to open the file, and it makes sense, using head or cat, but not using any sort of editor.
In the end, all I wish to do is open the file in emacs, delete the "messy" characters, and save it once cleaned up. The file, however, is huge, so I need something powerful like emacs to be able to open it.
Otherwise, I suppose I can try to create a script to read this in line by line, forcing the script to read it in text format, then write it. But I wanted something quick, since I won't be doing this over & over.
Thanks!
Mike
perl -i.bk -pe 's/[^[:ascii:]]//g;' file
Found this perl one liner here: http://www.perlmonks.org/?node_id=619792
Try M-xfind-file-literally in Emacs.
You could edit the file using hexl-mode, which lets you edit the file in hexadecimal. That would let you see precisely what those offending characters are, and remove them.
It sounds like you either got a different line ending in the file (eg: carriage returns on a *nix system) or it got saved in an unexpected encoding.
You could use strings to grab "printable characters in file". You might have to play with the --encoding though I have only ever used it to grab ascii strings from executable files.
I am using a perl script to read in a file, but I'm not sure what encoding the file is in. Basically, my file is a list of book titles, but each book has other info associated with it (author, publication date, etc). So each book title is within a discrete chunk of data for the book. So I iterate through the file line by line until I find the regular expression '/Book Title: (.*)/' and take what's in the paren. Then, I create a separate .txt file with the name of the text file being my book. However, in my unix server, when I look at the name of the file, it's actually not, for example, 'LordOfTheFlies.txt' but rather 'LordOfTheFlies^M.txt'
What is this '^M'? Is that a weird end of line encoding I'm not taking into account? I tried chomp but it doesn't seem to be working. What is the best file encoding for working with perl?
It's the additional carriage return character that Windows systems insert before line feed characters (M == 13th letter, hence ASCII 13 is visualised as ^M).
It has nothing to do with file encoding, it's just the line ending policy biting you. Perl is usually good at handling line ending characters correctly, but if they occur somewhere else than the end of a line you have to do it yourself. You can use s/\r// instead of chomp() to get them out.
Before processing the file, you need to know the encoding of the file, which is determined by the producer of the file.
That "^M" is control-M, which is a carriage return, and is not needed in Unix file systems.Looks like the file is created in Unix and transferred to Windows. It can also be added with ftp when text file are transfered as binaries.
Try chop, instead of 'chomp'. Chomp removes the 'new line character'. s/\r// is also good.
For your general question, you might want to use appropriate module for the file type you have to make your life easier and better with Perl.