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Full Discussion: Read files in shell script code and run a C program on those files
Top Forums Shell Programming and Scripting Read files in shell script code and run a C program on those files Post 302854265 by shoaibjameel123 on Tuesday 17th of September 2013 03:47:04 AM
Old 09-17-2013
Read files in shell script code and run a C program on those files
HI,

I am trying to implement a simple shell script program that does not make use of ls or find commands as they are quite expensive on very large sets of files. So, I am trying to generate the file list myself. What I am trying to do is this:

1. Generate a file name using shell script, for example, 1.dat, 2.dat,..., so on.

2. Call a C program within the for-loop in that shell program. The C program reads the file name in argv [ 1 ], which is defined within the program.

3. Loop until all files have been read by the C program.

This is what I have done.

My original shell script was this:
Code:
ls -1 *.dat | while read page
do
  c_program.out $page>$page.txt
done
rename .dat.txt .dat *.dat.txt

But the above script is very slow when the number of files is really really big. SO I am now trying to do this:

Code:
for i in {1..5}
do
        var=`$i.dat`
        c_program.out $var > $i.txt
done
rename .txt .dat *.txt

But when I run the shell script, I get the following errors:

Code:
shelll_script.sh: line 3: ./1.dat: Permission denied
shelll_script.sh: line 3: ./2.dat: Permission denied
shelll_script.sh: line 3: ./3.dat: Permission denied
shelll_script.sh: line 3: ./4.dat: Permission denied
shelll_script.sh: line 3: ./5.dat: Permission denied

I am using Linux with BASH.
 

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LEARN ABOUT DEBIAN

plotit

plotit(1)						      General Commands Manual							 plotit(1)

NAME

       plotit - experiment data visualization

SYNOPSIS

       plotit -w FILE
       plotit [-lp] -q FILE [FILE]...
       plotit [-lp] Y FILE [FILE...]
       plotit [-lp] X Y FILE [FILE...]

DESCRIPTION

       The  plotit program is a simple plotting program which can draw line plots and stripcharts using a command language similar to that of gnu-
       plot.  It can also make quick plots of multiple data files from the command-line.  Wildcards may be used in the file names.

       The program takes optional expressions which can be used to manipulate data columns before plotting.  Expressions may be as simple  as  the
       designation  of	a  column  to  be  plotted or may contain arithmetic expressions and functions.  In the latter case the espression must be
       enclosed in 'single' or "double" quotation marks. Column numbers are designated by the at-sign character (@).  A single expression is  used
       for the Y axis of the plot.

OPTIONS

       -h, --help
	      Print the usage and exit.

       --version
	      Print the version number and exit.

       -w     Watch  the input file for commands to stripchart, or wait to read all of stdin before plotting.  Only one file or - for stdin may be
	      specified with this option.  No other options may be used in conjuction with this option.

       -q     Plot the first and second columns of each file.

       -l     Plot with lines.

       -p     Plot with points.

EXAMPLES

       Plot the second column versus the first of all three files with lines only.

	      plotit -lq file1.dat file2.dat file3.dat

       Plot the quotient of the third column and the second column versus the first column of all files matching the pattern using points only.

	      plotit -p '@3/@2' file??.dat

       Plot the natural log of the second column divided by the third column versus the fourth column.	By default these  data	are  plotted  with
       both lines and points.

	      plotit @4 'log(@2/@3)' file.dat

AUTHOR

       This manual page was written by Carlo Segre <segre@iit.edu>.

								 February 21, 2009							 plotit(1)
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