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Old 09-25-2008, 06:46 AM   #1
Registered: Jan 2007
Location: Netherlands, The
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Unhappy Search values within multiple files line to line

Hello guys (and girls),

I've got the following script:



while read line
        F1=$(echo $line| grep '#00010' | cut -d$FS -f7)
        if [ -z $F1 ] ; then
          echo $F1
done < $FILE
In this script it reads one file, but I want to read a lot of files. I've got one directory with multiple files and directories. So this script has to read al those files and process line to line.

I was puzzeling with this script, I've got this:



for files in `find /opt/. -name "*.txt";
	while read line
			F1=$(echo $line| grep '#00010' | cut -d$FS -f7)
			if [ -z $F1 ] ; then
				echo $F1
	done < $files
This doesn't work, can anyone help me please?!


Last edited by Chrizzieej; 09-25-2008 at 07:11 AM.
Old 09-25-2008, 07:48 AM   #2
Registered: Feb 2008
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I don't know if it is the only problem, or maybe a mistake while typing, but the row
for files in `find /opt/. -name "*.txt";
is wrong, you forgot a ` and in /opt/. the dot is pointless. That should be
for files in `find /opt -name "*.txt"`;
Old 09-25-2008, 08:06 AM   #3
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You're on the right track to wrap the while loop which processes lines in the for loop which processes the files; but, at the very least, you forgot the closing '`' in:
for files in `find /opt/. -name "*.txt";
### output from my command line:
$ for files in `find /opt/. -name "*.txt";
> do
>         echo $files
> done
### ^C to regain control of the xterm

$ for F in `find /opt/. -name "*.txt"`;
> do
>    echo $F
> done

If I may be so bold, let me offer some suggestions about programming style:
  • Indenting with tabs spreads your code too much, making it hard to read. The point of indenting, even in Python, is to make the code easier for humans to read &, therefore, to understand. I've found that 3 spaces is ideal for (most) bash scripts.

  • The bash convention is to use all upper case for variable names.

  • Long, (lower case), self documenting variable names may work in C, but where all instances of a variable are on 1 page, how hard is it to figure out what it means? If I start a loop w/ "for F in <list_of_files>", does it take a degree in rocket science to figure out that "$F" is the current file?

  • In any case "files" is plural & should not be used to stand for the, singular, current instance. You should at least be able to use "for FILE in $FILES ...".
Old 09-25-2008, 08:16 AM   #4
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If you have Python, here's an alternative
#!/usr/bin/env python
import sys,os
for ROOT,DIR,FILES in os.walk(directory):
    for fi in FILES:
        if fi.endswith(".txt"):
            for lines in open(os.path.join(ROOT,fi)):
                if "#00010" in lines:
                        print "File ", os.path.join(ROOT,fi), " has field 7: ",f7
Old 09-25-2008, 08:34 PM   #5
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Actually, style is purely subjective

But I would say (slightly different)

Bash CONSTANTS in uppercase, other vars in lower-with-underscores.
Re the latter, just about all real progs I've worked on get longer/more complex sooner or later, and consistency is better.
Old 09-26-2008, 05:11 PM   #6
Registered: Jun 2008
Posts: 235

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about your syntax error the others always wrote. But I'm confused with your read loop: As far as I understand, you want to print field 7 as long as the lines contain the "#00010" character sequence and you want to stop reading the file at the first line, which does not contain this sequence?

Using your solution you are starting 2 sub shells and 2 external programs for each line - a lot of processes for large files!

You should better think about a specialised program like sed or awk (untested):
awk -F'#' /#00010/ { print $7; getline; }
          { nextfile; } ' `find /opt -name '*.txt' -print`
2 processes in summary for all files.



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