How to create the grep -v command in Perl, here is the clue :
[pene@donunix] perl -ne "! /your_string/ && print" file.txt
And if you want to write the output directly into the input file (file.txt), just type this :
[pene@donunix] perl -i.bak -ne "! /your_string/ && print" file.txt
In the following example file « calc.txt », I want to multiply each number by 2/3 :
199,119
326,147
385,345
250,330
157,218
67,241
402,175
Here is the solution in one line with Perl :
[pene@donunix] perl -pi.bak -e 's|(\d+),(\d+)|int($1*2/3).",".int($2*2/3)|e' calc.txt
[pene@donunix] var=`echo $var | tr [a-z] [A-Z]`
How to display all lines with the word text or the word name?
Here is the answer:
[pene@donunix] grep -P 'text|name' file.txt
How to substitute all pattern1 to pattern2 from the 3rd line to the 20st line?
Perl has the solution... and in one line :D
[pene@donunix] perl -p -i -e "s|pattern1|pattern2| if 3 .. 20" file.txt
I have some problem with the wc command.
If I write just 3 characters in a file, wc -m give to me 4 characters instead of 3.
For example :
[pene@donunix] echo 123 | wc -m
4
To explain quickly this, wc add the "end of line" character. So, if I don't want it for my echo 123, I have to write this :
[pene@donunix] echo -e "123\c" | wc -m
And if I want to exclude all the end_of_line/return characters of my wc -c, I have to write this wonderful command :
[pene@donunix] cat fic.txt | xargs -i% echo -e "%\c" | wc -c
How replace the expression expr1 by expr2 in all the html files located from the current directory and all his sub-directories :
[pene@donunix] find . -name "*.html" -print0 | xargs -0 perl -p -i -e 's|expr1|expr2|g'
Search the occurence occur in *.pro files, and print only the name of files where the occurence was found.
[pene@donunix] grep occur *.pro | sed -e 's/\(.*\.pro\):.*/\1/' | uniq
in this code, we change in all IDL *.pro files, the path ../DATA onto a variable named data_toolbox.
For more precisions, the occurence '../DATA is replaced by data_toolbox+'
Here is the code :
[pene@donunix] perl -p -i.bak -e "s|\'\.\./DATA|toolbox_data+\'|g" *.pro
NB : Before making the changes, perl create a copy of the IDL files with the extension .bak.
Here is a Perl one-line command to create an html thumb page.
Then in the html thumb page you will be able to visualise gifs from a specific directory :
The code :
[pene@donunix] ls -1 *.jpg *.gif *.png > index.html
[pene@donunix] perl -p -i.bak -e 's/^(.*)\.(.{3})$/<a href="$1\.$2"><img src="$1\.$2" width="320" border="0" alt="$1" ><\/a><br\/>/g' index.html
Well done, you've created an index.html file in your pictures directory.
