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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 OSF1

dh_installdeb

DH_INSTALLDEB(1)						     Debhelper							  DH_INSTALLDEB(1)

NAME

       dh_installdeb - install files into the DEBIAN directory

SYNOPSIS

       dh_installdeb [debhelperoptions]

DESCRIPTION

       dh_installdeb is a debhelper program that is responsible for installing files into the DEBIAN directories in package build directories with
       the correct permissions.

FILES

       package.postinst
       package.preinst
       package.postrm
       package.prerm
	   These maintainer scripts are installed into the DEBIAN directory.

	   Inside the scripts, the token #DEBHELPER# is replaced with shell script snippets generated by other debhelper commands.

       package.triggers
       package.shlibs
	   These control files are installed into the DEBIAN directory.

	   Note that package.shlibs is only installed in compat level 9 and earlier.  In compat 10, please use dh_makeshlibs(1).

       package.conffiles
	   This control file will be installed into the DEBIAN directory.

	   In v3 compatibility mode and higher, all files in the etc/ directory in a package will automatically be flagged as conffiles by this
	   program, so there is no need to list them manually here.

       package.maintscript
	   Lines in this file correspond to dpkg-maintscript-helper(1) commands and parameters.  However, the "maint-script-parameters" should not
	   be included as debhelper will add those automatically.

	   Example:

	       # Correct
	       rm_conffile /etc/obsolete.conf 0.2~ foo
	       # INCORRECT
	       rm_conffile /etc/obsolete.conf 0.2~ foo -- "$@"

	   In compat 10 or later, any shell metacharacters will be escaped, so arbitrary shell code cannot be inserted here.  For example, a line
	   such as "mv_conffile /etc/oldconffile /etc/newconffile" will insert maintainer script snippets into all maintainer scripts sufficient
	   to move that conffile.

	   It was also the intention to escape shell metacharacters in previous compat levels.	However, it did not work properly and as such it
	   was possible to embed arbitrary shell code in earlier compat levels.

	   The dh_installdeb tool will do some basic validation of some of the commands listed in this file to catch common mistakes.  The
	   validation is enabled as a warning since compat 10 and as a hard error in compat 12.

SEE ALSO

       debhelper(7)

       This program is a part of debhelper.

AUTHOR

       Joey Hess <joeyh@debian.org>

11.1.6ubuntu2							    2018-05-10							  DH_INSTALLDEB(1)
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