Can we do multiple substitutions with a single Perl command? - regex

Is there a way to make the following into one perl -pe instead of piping it in sequence?
cat text.txt | perl -pe "s/PATTERN1/$PATTERN1/g" | perl -pe "s/PATTERN2/$PATTERN2/g"


The answer in the comments is perfect, but here's a goofy way to do it just for fun:
perl -pe '$_ = s/PATTERN1/$PATTERN1/gr =~ s/PATTERN2/$PATTERN2/gr' text.txt
Anyway, so you don't need to use pipes at all. Just add the file name as the last argument.
Just for reference, here is the best answer, which was given above in the comments:
perl -pe 's/PATTERN1/$PATTERN1/g; s/PATTERN2/$PATTERN2/g' text.txt

Related

Swap columns in bash using SED without using loop

I'm new to Sed, I'm trying to learn some pattern using Sed.
I got a filenamne.txt that has the following entry:
ppp/jjj qqq/kkk rrr/lll
My goal is to swap the word before the slash and the word after the slash in each of the three word1/word2 columns:
jjj/ppp kkk/qqq lll/rrr
I tried using sed –re ‘s!(.*)(/)(.*)!\1\2\!’ filename.txt, but it didn't work. Any idea how can I go about it?

$ echo "ppp/jjj qqq/kkk rrr/lll" | sed -e 's/$/ /' -e 's!\([^/]*\)/\([^ ]*\) !\2/\1 !g'
jjj/ppp kkk/qqq lll/rrr

Use replacement in perl command-line is a lot more straight-forward :-
perl -pe 's/(\w+)\/(\w+)/$2\/$1/g' file
jjj/ppp kkk/qqq lll/rrr

$ sed 's#\([^ ]*\)/\([^ ]*\)#\2/\1#g' file
jjj/ppp kkk/qqq lll/rrr

One-liner to print all lines between two patterns

Using one line of Perl code, what is the shortest way possible to print all the lines between two patterns not including the lines with the patterns?
If this is file.txt:
aaa
START
bbb
ccc
ddd
END
eee
fff
I want to print this:
bbb
ccc
ddd
I can get most of the way there using something like this:
perl -ne 'print if (/^START/../^END/);'
That includes the START and END lines, though.
I can get the job done like this:
perl -ne 'if (/^START/../^END/) { print unless (/^(START)|(END)/); };' file.txt
But that seems redundant.
What I'd really like to do is use lookbehind and lookahead assertions like this:
perl -ne 'print if (/^(?<=START)/../(?=END)/);' file.txt
But that doesn't work and I think I've got something just a little bit wrong in my regex.
These are just some of the variations I've tried that produce no output:
perl -ne 'print if (/^(?<=START)/../^.*$(?=END)/);' file.txt
perl -ne 'print if (/^(?<=START)/../^.*(?=END)/);' file.txt
perl -ne 'print if (/^(?<=START)/../(?=END)/);' file.txt
perl -ne 'print if (/^(?<=START)/../.*(?=END)/);' file.txt
perl -ne 'print if (/^(?<=START)/../^.*(?=END)/);' file.txt
perl -ne 'print if (/^(?<=START)/../$(?=END)/);' file.txt
perl -ne 'print if (/^(?<=START)/../^(?=END)/);' file.txt
perl -ne 'print if (/^(?<=START)/../(?=^END)/);' file.txt
perl -ne 'print if (/^(?<=START)/../.*(?=END)/s);' file.txt

Read the whole file, match, and print.
perl -0777 -e 'print <> =~ /START.*?\n(.*?)END.*?/gs;' file.txt
May drop .*? after START|END if alone on line.
Then drop \n for a blank line between segments.
Read file, split line by START|END, print every odd of #F
perl -0777 -F"START|END" -ane 'print #F[ grep { $_ & 1 } (0..$#F) ]' file.txt
Use END { } block for extra processing. Uses }{ for END { }.
perl -ne 'push #r, $_ if (/^START/../^END/); }{ print "#r[1..$#r-1]"' file.txt
Works as it stands only for a single such segment in the file.

It seems kind of arbitrary to place a single-line restriction on this, but here's one way to do it:
$ perl -wne 'last if /^END/; print if $p; $p = 1 if /^START/;' file.txt

perl -e 'print split(/.*START.|END.*/s, join("", <>))' file.txt
perl -ne 'print if /START/../END/' file.txt | perl -ne 'print unless $.==1 or eof'
perl -ne 'print if /START/../END/' file.txt | sed -e '$d' -n -e '1\!p'

I don't see why you are so insistent on using lookarounds, but here are a couple of ways to do it.
perl -ne 'print if /^(?=START)/../^(?=END)/'
This finds the terminators without actually matching them. A zero-length match which satisfies the lookahead is matched.
Your lookbehind wasn't working because it was trying to find beginning of line ^ with START before it on the same line, which can obviously never match. Factor the ^ into the zero-width assertion and it will work:
perl -ne 'print if /(?<=^START)/../(?<=^END)/'
As suggested in comments by #ThisSuitIsBlackNot you can use the sequence number to omit the START and END tokens.
perl -ne '$s = /^START/../^END/; print if ($s>1 && $s !~ /E0/)'
The lookarounds don't contribute anything useful so I did not develop those examples fully. You can adapt this to one of the lookaround examples above if you care more about using lookarounds than about code maintainability and speed of execution.

BASH: replacing PERL with SED for in-place substitution

Would like to replace this statement with perl:
perl -pe "s|(?<=://).+?(?=/)|$2:80|"
with
sed -e "s|<regex>|$2:80|"
Since sed has a much less powerful regex engine (for example it does not support look-arounds) the task boils down to writing a sed compatible regex to match only a domain name in a fully qualitied URL. Examples:
http://php2-mindaugasb.c9.io/Testing/JS/displayName.js
http://php2-mindaugasb.c9.io?a=Testing.js
http://www.google.com?a=Testing.js
Should become:
http://$2:80/Testing/JS/displayName.js
http://$2:80?a=Testing.js
http://$2:80?a=Testing.js
A solution like this would be ok:
sed -e "s|<regex>|http://$2:80|"
Thanks :)

Use the below sed command.
$ sed "s~//[^/?]\+\([?/]\)~//\$2:80\1~g" file
http://$2:80/Testing/JS/displayName.js
http://$2:80?a=Testing.js
http://$2:80?a=Testing.js
You must need to escape the $ at the replacement part.

sed 's|http://[^/?]*|http://$2:80|' file
Output:
http://$2:80/Testing/JS/displayName.js
http://$2:80?a=Testing.js
http://$2:80?a=Testing.js

perl regex to extract a specifc word

I have the following exmaple of a text file:
AFUA_2G08360|pyrG
AFUA_2G12630
gel1|bgt2|AFUA_2G01170
and I wish to do a regex to filter out AFUA_2G08360, AFUA_2G12630, AFUA_2G01170 using perl -l -ne in unix command line.
How would you suggest to do that?

why not using 'sed' with something like
sed 's/AFUA_2G\d{5}//'

Try this expression:
/(AFUA_2G\d+)/g

Here is a doable one-liner for your example input.
cat data | perl -l -e 'while (<>) {s/.*(AFUA_[^\|]*).*/\1/g; print}'

AFUA_[0-9A-Za-z]{7}
See here : http://regexr.com?328gj
Command line :
user#mch:/tmp$ cat input.txt
AFUA_2G08360|pyrG
AFUA_2G12630
gel1|bgt2|AFUA_2G01170
user#mch:/tmp$ cat input.txt | perl -lne "#matches = /AFUA_[0-9A-Za-z]{7}/g; print join("\n", #matches)";
AFUA_2G08360
AFUA_2G12630
AFUA_2G01170

use
perl -pe 's/.*(AFUA_[0-9a-zA-Z]*).*$/\1/' your_file
tested:
> cat temp
AFUA_2G08360|pyrG
AFUA_2G12630
gel1|bgt2|AFUA_2G01170
> perl -pe 's/.*(AFUA_[0-9a-zA-Z]*).*$/\1/' temp
AFUA_2G08360
AFUA_2G12630
AFUA_2G01170

Perl regex: remove everything (including line breaks) until a match is found

Apologies for the simple question. I don't clean text or use regex often.
I have a large number of text files in which I want to remove every line until my regex finds a match. There's usually about 15 lines of fluff before I find a match. I was hoping for a perl one-liner that would look like this:
perl -p -i -e "s/.*By.unanimous.vote//g" *.txt
But this doesn't work.
Thanks

Solution using the flip-flop operator:
perl -pi -e '$_="" unless /By.unanimous.vote/ .. 1' input-files
Shorter solution that also uses the x=!! pseudo operator:
per -pi -e '$_ x=!! (/By.unanimous.vote/ .. 1)' input-files

Have a try with:
If you want to get rid until the last By.unanimous.vote
perl -00 -pe "s/.*By.unanimous.vote//s" inputfile > outputfile
If you want to get rid until the first By.unanimous.vote
perl -00 -pe "s/.*?By.unanimous.vote//s" inputfile > outputfile

Try something like:
perl -pi -e "$a=1 if !$a && /By\.unanimous\.vote/i; s/.*//s if !$a" *.txt
Should remove the lines before the matched line. If you want to remove the matching line also you can do something like:
perl -pi -e "$a=1 if !$a && s/.*By\.unanimous\.vote.*//is; s/.*//s if !$a" *.txt
Shorter versions:
perl -pi -e "$a++if/By\.unanimous\.vote/i;$a||s/.*//s" *.txt
perl -pi -e "$a++if s/.*By\.unanimous\.vote.*//si;$a||s/.*//s" *.txt

You haven't said whether you want to keep the By.unanimous.vote part, but it sounds to me like you want:
s/[\s\S]*?(?=By\.unanimous\.vote)//
Note the missing g flag and the lazy *? quantifier, because you want to stop matching once you hit that string. This should preserve By.unanimous.vote and everything after it. The [\s\S] matches newlines. In Perl, you can also do this with:
s/.*?(?=By\.unanimous\.vote)//s

Solution using awk
awk '/.*By.unanimous.vote/{a=1} a==1{print}' input > output