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Full Discussion: Explain iconv command
Top Forums UNIX for Beginners Questions & Answers Explain iconv command Post 303032462 by Corona688 on Monday 18th of March 2019 06:32:22 PM
Old 03-18-2019
dd can pad newline-terminated records to appropriate lengths with spaces, but they must be newline-terminated. Here is a utility to convert to newline-terminated records:

Code:
// convert to an executable with cc block.c -o block
#include <stdio.h>
#include <limits.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
        long int BLOCK=0;
        char *buf=NULL;

        if(argc < 2)
        {
                fprintf(stderr, "usage:  %s blocksize [inputfile]\n", argv[0]);
                exit(1);
        }

        if(argc >= 2) BLOCK=strtol(argv[1], NULL, 10);
        if(argc >= 3) {
                if(freopen(argv[2], "rb", stdin)==NULL)
                {
                        perror("Couldn't open");
                        return(1);
                }
        }

        if(BLOCK<=0)
        {
                fprintf(stderr, "Invalid block size %ld\n", BLOCK);
                return(1);
        }

        buf=malloc(BLOCK+1);
        if(buf == NULL)
        {
                perror("Couldn't allocate");
                return(1);
        }

//      fprintf(stderr, "block size %ld\n", BLOCK);

        buf[BLOCK]='\n';
        while(fread(buf,BLOCK,1,stdin))
                fwrite(buf,BLOCK+1,1,stdout);

        free(buf);
        return(0);
}

Having done that, you can convert it with iconv, pad to the required length with dd, then remove the newlines with tr.

In my example, I delete capital letters from aAabBbcccdDdeeEfffggghhhiIijjjkkklLlmmmnnn without changing length.

Code:
#!/bin/sh

BLOCKSIZE=3

# Add newlines using block utility
./block $BLOCKSIZE |
        # Remove characters, i.e. you'd put iconv here
        tr -d 'A-Z' |
        # Pad shrunken records with spaces
        dd ibs=$BLOCKSIZE cbs=$BLOCKSIZE conv=sync,block 2>/dev/null |
        # Remove newlines
        tr -d '\n'

Code:
$ cat fixed.txt
aAabBbcccdDdeeEfffggghhhiIijjjkkklLlmmmnnn

$ ./dump.sh < fixed.txt
aa bb cccdd ee fffggghhhii jjjkkkll mmmnnn   

$

You end up with one blank record at the end, full of spaces, which I haven't figured out how to avoid yet.
 

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LEARN ABOUT REDHAT

pvmfstartpvmd

START_PVMD(3PVM)						  PVM Version 3.4						  START_PVMD(3PVM)

NAME

       pvm_start_pvmd - Starts new PVM daemon.

SYNOPSIS

       C    int info = pvm_start_pvmd( int argc, char **argv, int block )

       Fortran	 call pvmfstartpvmd( args, block, info )

PARAMETERS

       argc    Number of arguments in argv.

       argv    An array of arguments to the executable.

       args    A character string containing the arguments to the executable.

       args    A character string containing the arguments to the executable.

       block   Integer specifying whether to block until startup of all hosts complete or return immediately.

       info    Integer returning the error code.

DESCRIPTION

       The  routine  pvm_start_pvmd starts up a pvmd3 process, the master of a new virtual machine.  It returns as soon as the pvmd is started and
       ready for work.	If the block parameter is nonzero and a hostfile is passed to the pvmd as a parameter, it returns when all hosts marked to
       start have been added.  pvm_start_pvmd returns zero on success.

       If  PVM is compiled to allow running more than one pvmd per host, a task calling pvm_start_pvmd before any other pvm functions will connect
       to the pvmd that it starts.  pvm_start_pvmd sets environment variable PVMSOCK to the address printed by the pvmd as it starts up.

EXAMPLES

       C:
	    static char *argv[] = {
		"-d41",
		"/u/jones/pvmd_hosts",
	    };
	    argc = 2
	    info = pvm_start_pvmd( argc, argv, block );

       Fortran:
	    CALL PVMFSTART_PVMD( '-d41 /u/jones/pvmd_hosts', BLOCK, INFO )

EXAMPLES

       C:
	    static char *argv[] = {
		"-d41",
		"/u/jones/pvmd_hosts",
	    };
	    argc = 2
	    info = pvm_start_pvmd( argc, argv, block );

       Fortran:
	    CALL PVMFSTART_PVMD( '-d41 /u/jones/pvmd_hosts', BLOCK, INFO )

ERRORS

       The following error conditions can be returned

       PvmDupHost
	      A pvmd is already running.

       PvmSysErr
	      The local pvmd is not responding.

SEE ALSO

       pvm_addhosts(3PVM), pvmd3(1PVM) pvmd3(1PVM)

								 11 December, 1995						  START_PVMD(3PVM)
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