file: 'rwtest' mode: 'a' readSync: '' writeSync: '' bufferType: 'none' bufSize: '20'

set AAA [string repeat ABCDEFGHIJKLMNOPQRSTUVWXY 4]
set 123 [string repeat 1234567890 10]
set logFilename rwtest-a---none-20.log
set testFilename rwtest-a---none-20.test


set fd [open $testFilename {WRONLY APPEND CREAT TRUNC}]
puts $fd $AAA
puts $fd $123
close $fd

set fd [open rwtest-a---none-20.test a+]
fconfigure $fd -buffering none -buffersize 1024

foreach num {1 2 3 4 5} {
    
    set start [tell $fd]
    puts -nonewline $fd [string repeat $num 11]
    set end [tell $fd]
    
    set repos [tell $fd]
    set char [read $fd 1]
    set final [tell $fd ]
    puts $logFd "$num start = $start end = $end repos = $repos final = $final char = $char"
}
    
close $fd

set fd2 [open rwtest-a---none-20.test r ]
set contents [read $fd2]
close $fd2
puts $logFd \n$contents

1 start = 202 end = 213 repos = 213 final = 213 char = 
2 start = 213 end = 224 repos = 224 final = 224 char = 
3 start = 224 end = 235 repos = 235 final = 235 char = 
4 start = 235 end = 246 repos = 246 final = 246 char = 
5 start = 246 end = 257 repos = 257 final = 257 char = 

ABCDEFGHIJKLMNOPQRSTUVWXYABCDEFGHIJKLMNOPQRSTUVWXYABCDEFGHIJKLMNOPQRSTUVWXYABCDEFGHIJKLMNOPQRSTUVWXY
1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
1111111111122222222222333333333334444444444455555555555