Perl on the fly

To replace string in a file on the fly using perl simply enter in the command line the following:

% perl -p -i -e 's/one/two/g' file

The script simply replace all entries of "one" with "two".

find command

http://www.grymoire.com/Unix/Find.html#uh-0

renaming files using perl

This is an example of how to rename a set of files that match a particular pattern.

#!/usr/bin/perl
use File::Find;
use File::Path;

die "usage:$0 (DIR)\n" unless @ARGV;
$dir = $ARGV[0];

finddepth(\&edits, $dir);
exit(0);


sub edits {
$fname = $_;
if (-f) {
if ($fname =~/[^\s].\.(cnf|dnf|eps|etat|planches)$/) {
print "Scanning $fname\n";
#$newname = $fname;
#$newname=~s/(.\./test_$1/;

my @values = split(/\./, $fname);
#foreach my $val (@values) {
#print "$val\n";
#}
my $pref=@values[0];
my $suff=@values[1];
$newname="test_" . $pref . "." .$suff;
print "$newname\n";
rename ($fname, $newname)

}
}
}

File line ending from DOS to UNIX or MAC

Alt+x set-buffer-file-coding-system

Short cut : CTRL X ret F

Remove leading and trailing whitespace

To remove leading and trailing whitespace(or any trailing char):

• Regular Expression :
• s/^\s+//;
• s/\s+$//;
• Perl :
• Chomp();
• Python:
• strip();
  

How to read and write text file in python

list1=file("filename.txt").readlines() #don't forget the parenthesis
set1=set(liste1) #cast it to a set

set1=[elem.strip() for elem in set1] #strip all the elements of the set by removing trailing characters such us /t or /n

To find the differences with another set :
set3=set1.difference(set2)

To save into a file
fLog=tFile.open('filename.log','w')

First I add line return to each elem of the set
set4=[elem+"\n" for elem in set3]

Then I write the whole set into the file:

fLog.writelines(set4)
fLog.close()

top list of processes

command : top -u
OS : Linux & Mac OS
list the top running processes