The reason is when you pipe the file to a while loop, it actually gets executed in a sub-shell:-
So the scope of the variable sum value is within the while loop. This is the reason why it prints 0 outside the while loop
You can resolve this by removing the pipe:-
Being a Korn shell user, myself, I often overlook the pipe / sub-shell thing in Bash.. it's good that you pointed that out to the OP
Can I use the read command to read the contents of a variable? I'm trying by using the following code and getting nothing back. I'm in a Linux environment.
#!/bin/ksh
IFS=~
VAR1=1~2~3~4
echo $VAR1 | read a b c d
print "$a $b $c $d" (9 Replies)
# include <stdio.h>
# include <fcntl.h>
# include <stdlib.h>
# include <sys/stat.h>
int main(int argc, char *argv)
{
int fRead, fPadded, padVal;
int btRead;
int BUFFSIZE = 512;
char buff;
if (argc != 4)
{
printf ("Please provide all of the... (3 Replies)
Hi the following c-code utilizing the 'read()' man 2 read method cant read in files larger that 2gig.
Hi I've found a strange problem on ubuntu64bit, that limits the data you are allowed to allocate on a 64bit platform using the c function 'read()'
The following program wont allow to allocate... (14 Replies)
Hi Guys,
Happy New Year to you all!
I have a requirement to read an embedded new-line using KSH's read builtin.
Here is what I am trying to do:
run_sql "select guestid, address, email from guest" | while read id addr email
do
## Biz logic goes here
done
I can take care of any... (6 Replies)
hi,
this is my script #!/bin/ksh
cat temp_file.dat | while read line
do
read test
if ]; then
break
else echo "ERROR"
fi
done
when i execute this code , the script does wait for the user input . it directly prints "ERROR" and terminates after the no. of times as there... (3 Replies)
Hello All,
i am a newbie and need some help when reading a csv file in a bourne shell script. I want to read 10 lines, then wait for a minute and then do a reading of another 10 lines and so on in the same way. I want to do this till the end of file.
Any inputs are appreciated
... (3 Replies)
Hi
i am looking a way to look at a log file(log.txt) from the last time I've read it.
However after some days the main log file(log.txt) is rename to (log.txt.1).
So now i will have two log files as below.
log.txt.1
log.txt
Now, i have to read the log from the point where i have left... (3 Replies)
Hi
I am new to writing script and want to use a Bash Piped while-read and read from user input.
if something happens on server.log then do while loop or if something happend on user input then do while loop.
Pseudocode something like:
tail -n 3 -f server.log | while read serverline || read... (8 Replies)
Hi,
I am facing issues with the below:
I have a lookup file say lookup.lkp.This lookup.lkp file contains strings delimited by comma(,).
Now i want to read this command from file and execute it.
So my code below is :
Contents in the lookup.lkp file is :
c_e,m,a,`cd $BOX | ls cef_*|tail... (7 Replies)
Hi.
How can I create a history function? (By "read" command or so)
&
How can I configure a read command so that the arrow keys are not displayed so funny? (^[[A)
Thanks in advance. (4 Replies)
Discussion started by: sinnlosername
4 Replies
LEARN ABOUT OSX
sum
sum(n) Cyclic Redundancy Checks sum(n)
__________________________________________________________________________________________________________________________________________________NAME
sum - Calculate a sum(1) compatible checksum
SYNOPSIS
package require Tcl 8.2
package require sum ?1.1.0?
::crc::sum ?-bsd | -sysv? ?-format fmt? ?-chunksize size? [ -filename file | -channel chan | string ]
_________________________________________________________________DESCRIPTION
This package provides a Tcl-only implementation of the sum(1) command which calculates a 16 bit checksum value from the input data. The
BSD sum algorithm is used by default but the SysV algorithm is also available.
COMMANDS
::crc::sum ?-bsd | -sysv? ?-format fmt? ?-chunksize size? [ -filename file | -channel chan | string ]
The command takes string data or a file name or a channel and returns a checksum value calculated using the sum(1) algorithm. The
result is formatted using the format(n) specifier provided or as an unsigned integer (%u) by default.
OPTIONS -sysv The SysV algorithm is fairly naive. The byte values are summed and any overflow is discarded. The lowest 16 bits are returned as the
checksum. Input with the same content but different ordering will give the same result.
-bsd This algorithm is similar to the SysV version but includes a bit rotation step which provides a dependency on the order of the data
values.
-filename name
Return a checksum for the file contents instead of for parameter data.
-channel chan
Return a checksum for the contents of the specified channel. The channel must be open for reading and should be configured for
binary translation. The channel will no be closed on completion.
-chunksize size
Set the block size used when reading data from either files or channels. This value defaults to 4096.
-format string
Return the checksum using an alternative format template.
EXAMPLES
% crc::sum "Hello, World!"
37287
% crc::sum -format 0x%X "Hello, World!"
0x91A7
% crc::sum -file sum.tcl
13392
AUTHORS
Pat Thoyts
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category crc of
the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for
either package and/or documentation.
SEE ALSO
cksum(n), crc32(n), sum(1)KEYWORDS
checksum, cksum, crc, crc32, cyclic redundancy check, data integrity, security, sum
CATEGORY
Hashes, checksums, and encryption
COPYRIGHT
Copyright (c) 2002, Pat Thoyts <patthoyts@users.sourceforge.net>
crc 1.1.0 sum(n)