awk or perl Post: 302251565

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Top Forums Shell Programming and Scripting awk or perl Post 302251565 by otheus on Monday 27th of October 2008 12:37:17 PM

10-27-2008

Registered User

Normally, one doesn't use awk or perl to read files in subfolders -- that's usually taken care of by the command line. In perl, it's possible to use the File::Find module (do a man on File::Find). But I find that module confusing and unwieldy, especially when you just want to read all the files in a directory. Better use a find pipeline into a "while read file; do perl .... $file; done" loop, or use xargs to similar effect.

Concerning question #1, do you need to plot the columns from each file separately, or do you need to aggregate them in some way? That is, all from one folder, all together, etc. If it's the latter, it might make more sense to import that data into a, for instance, MySQL database. Otherwise, you'll need to specify the command line with every single file in each group. (Or use the File::Find module with perl).

Concerning 2. You don't "plot" anything with perl/awk. You do that with another tool, such as gplot. If you want to use file2 (sender.dat) together with file1 (router2.dat), you can simply merge them together with sort:

Code:

sort -k 1n,2 file1 file2

The output should go to a temporary file or be piped into awk/perl, which can then do the interprolation. Unfortunately, I cannot interpret your formula for y. Especially the y[i+1] bit. With awk and perl, you can look *behind* a line, but ahead of one. So it would be better if you re-do the formula in terms of i and i-1.

otheus

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LEARN ABOUT V7

join

JOIN(1) 						      General Commands Manual							   JOIN(1)

NAME

       join - relational database operator

SYNOPSIS

       join [ options ] file1 file2

DESCRIPTION

       Join  forms,  on the standard output, a join of the two relations specified by the lines of file1 and file2.  If file1 is `-', the standard
       input is used.

       File1 and file2 must be sorted in increasing ASCII collating sequence on the fields on which they are to be joined, normally the  first	in
       each line.

       There  is  one line in the output for each pair of lines in file1 and file2 that have identical join fields.  The output line normally con-
       sists of the common field, then the rest of the line from file1, then the rest of the line from file2.

       Fields are normally separated by blank, tab or newline.	In this case, multiple separators count as one, and leading  separators  are  dis-
       carded.

       These options are recognized:

       -an    In addition to the normal output, produce a line for each unpairable line in file n, where n is 1 or 2.

       -e s   Replace empty output fields by string s.

       -jn m  Join on the mth field of file n.	If n is missing, use the mth field in each file.

       -o list
	      Each  output line comprises the fields specifed in list, each element of which has the form n.m, where n is a file number and m is a
	      field number.

       -tc    Use character c as a separator (tab character).  Every appearance of c in a line is significant.

SEE ALSO

       sort(1), comm(1), awk(1)

BUGS

       With default field separation, the collating sequence is that of sort -b; with -t, the sequence is that of a plain sort.

       The conventions of join, sort, comm, uniq, look and awk(1) are wildly incongruous.

																	   JOIN(1)

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