topic Re: Calculating byte size in a directory in Operating System - Linux

Calculating byte size in a directory

Henry Chua — Sun, 24 Jul 2005 20:50:08 GMT

Hi guys

Is it possible to write a program in C to calculate the byte size in a directory?

Regards
Henry

Re: Calculating byte size in a directory

Rajeev Shukla — Sun, 24 Jul 2005 21:00:16 GMT

Yes what you could do is write a program to open the directory read all the files in that directory and then use the stat() function in C which gives you a pointer to structure and get "st_size file size in bytes" add all of them for all the files.
That will return you the total bytes used by the directory, something smiliar to du command

Cheers
Rajeev

Re: Calculating byte size in a directory

Ralph Grothe — Mon, 25 Jul 2005 01:34:44 GMT

As said, this boils down to combining these syscalls

opendir(), readdir(), closedir(), stat()

Re: Calculating byte size in a directory

Muthukumar_5 — Mon, 25 Jul 2005 03:37:25 GMT

You can use stat() as,

#include
#include
#include

main()
{
int rc;
struct stat buf;
rc=stat("/tmp/block",&buf);
if ( rc==0 ) {
printf ("File size = %d bytes\n",buf.st_size);
} else {
printf ("Error\n");
}
}

cc -o block block.c
./block

change name /tmp/block to some others.

You can also use du -b . Sample example c program is available as,
http://www.phim.unibe.ch/comp_doc/c_manual/C/EXAMPLES/stat.c

hth.

Re: Calculating byte size in a directory

Geoff Wild — Mon, 25 Jul 2005 07:39:44 GMT

ere's one using awk

# cat /home/root/llsum
#!/bin/sh
#
# Program: /scripts/llsum
# By: Geoff wild
# Usage: llsum
#
# Displays a truncated "ll" listing and displays size
# statistics of the files in the listing
#
# FYI
# %s means we are printing a string
# %d means we are printing an integer
#
# Awk field numbers:
# $1 $2 $3 $4 $5 $6 $7 $8 $9
# -rwx------ 1 root sys 774 Feb 24 12:07 llsum
#
ls -al $* |\
awk 'BEGIN { x=i=0; printf "%-16s%-10s%8s%8s\n",\
"FILENAME","OWNER","SIZE","TYPE" }

# Print owner, size, and type. Then sum the size.
$1 ~ /^[-dlps]/ { # line format for normal files
printf "%-16s%-10s%8d",$9,$3,$5
x = x + $5
i++
}
# If the line starts with a - its a regular file; d is
# directory, etc.
$1 ~ /^-/ { printf "%8s\n","file" } # standard file types
$1 ~ /^d/ { printf "%8s\n","dir" }
$1 ~ /^l/ { printf "%8s\n","link" }
$1 ~ /^p/ { printf "%8s\n","pipe" }
$1 ~ /^s/ { printf "%8s\n","socket" }
$1 ~ /^[bc]/ { #line format for device files
printf "%-16s%-10s%8s%8s\n",$10,$3,"","dev"
}
END { printf "\nThese files occupy %d bytes (%.4f Mbytes)\n",\
x, x / (1024*1024)
printf "Average file size is %d bytes\n", x/i
}'

Rgds...Geoff

Re: Calculating byte size in a directory

Henry Chua — Mon, 25 Jul 2005 09:21:56 GMT

Hi guys,

How do i used opendir and readdir to list out all the files in a directory...

Best regards
Henry

Re: Calculating byte size in a directory

A. Clay Stephenson — Mon, 25 Jul 2005 11:14:19 GMT

Man opendir. It has an example of the use of opendir and readdir.