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visits member for 4 years, 9 months
seen Apr 10 at 20:41
Long-time Informix user and developer, experienced in C and Unix (many variants). Email: jonathan.leffler@gmail.com

May
6
answered compare file timestamp in bash
May
6
comment CPU I/O communication
@b-gen-jack-o-neill: for an IN or OUT instruction, the memory would (normally) ignore the request because the I/O pin is asserted. With memory mapped I/O, there is no RAM at the address - the I/O device is mapped there. So, the net result is "no, what is written goes to the I/O device". If someone misdesigned the memory system, I suppose you might have memory paying attention to the I/O request, but chaos will ensue -- does the I/O device or the memory win on an IN instruction where the memory tries to provide an answer as well as the I/O device. It won't work, and hence you won't see it.
May
2
revised CPU I/O communication
Fix trivial typo
May
1
answered CPU I/O communication
Apr
29
answered How can I still see the 'man' text after I quit man?
Apr
26
answered How are PID's generated?
Apr
25
answered rm -rf not erasing directory
Apr
18
revised xargs command works on ubuntu, but not mac
Tighten up the characterizatin of the first grep command
Apr
18
comment xargs command works on ubuntu, but not mac
@Corey: Is '${today}' something like '17/04/2010'? If so, you need to change the 's///' notation to 's%%%' instead - using the % or another character that does not appear in either pattern to separate the parts of the substitute operation. I'm not sure how you get 'sed' thinking there's a change command in the mix. You're right; xargs fixes things so that the executed command has /dev/null for its input, and the file names to be operated on as arguments. What's wrong with the Mac term that isn't fixed by switching from tcsh to a sane shell? And which do you prefer on the other system?
Apr
18
comment Need a Linux command that takes much time
That's a hard way of doing 'sleep 10'?
Apr
17
answered xargs command works on ubuntu, but not mac
Apr
12
revised Would running sudo rm -rf / in OS X wipe out any attached time machine backups?
Fix trivial typo
Apr
11
comment Which file systems support newlines in file names?
When Steve Bourne was testing his shell, he had a directory with 254 single-character file names in it - and it wrought havoc on programs that were not expecting such characters in file names.
Apr
11
answered Would running sudo rm -rf / in OS X wipe out any attached time machine backups?
Apr
8
answered find . -exec grep -l 'string' {} \; -print 2>/dev/null
Mar
29
comment stdout and stderr of script doesn't get redirected when executed by cron
@Chris: yes - my statement is too sweeping and your analysis is correct. Thanks.
Mar
28
answered stdout and stderr of script doesn't get redirected when executed by cron
Mar
25
comment su using here document
Note that the su command would not execute the second who - even if you managed to get past the password issue. It would either process the command given on its command line ('-c "command arg1 arg2"') or it would go interactive. Commands asking for a password usually read from your tty rather than from standard input - which means you have to fake it out (probably with 'expect' and a pseudo-tty).
Mar
23
comment Linux Kernel Messages: ata1.00: status: { DRDY ERR }
Your drive is already close to dead. I hope you have good backups, because it is a bit late now to do much about it.
Mar
22
comment How do you manage the user groups that users are assoicated to in Mac OS X?
That (dscl) is harder to use than the System Preferences, but it gives you greater control which is sometimes necessary.