02-14-2012
Thank you chihung for the fix.
So let me see if I understand this. I need to play tokenizer in my head to see this.
The parser sees the redirect token and sees that it is followed by a substitution string instead of something else like a directory path. Tokenizing on white-space (with parphrasing) it sees
... <stdout-redirect-append> <substitution-string>
instead of
... <stdout-redirect-append> <file-path> <stderr-redirect> <to-whereever-stdout-goes>
the <substitution-string> is internally processed as a <file-path> and since most characters, including spaces, can be in file names, the file name is "null 2>&1".
Subtle. A second parsing, after all string substitution would have reworked it, hence "eval".
Did I kinda get this right?
Thanks
John Morrison
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LEARN ABOUT DEBIAN
svscan
svscan(8) System Manager's Manual svscan(8)
NAME
svscan - starts and monitors a collection of services
SYNOPSIS
svscan [ directory ]
DESCRIPTION
svscan starts one supervise(8) process for each subdirectory of the current directory, up to a limit of 1000 subdirectories. svscan skips
subdirectory names starting with dots. supervise(8) must be in svscan's path.
svscan optionally starts a pair of supervise(8) processes, one for a subdirectory s, one for s/log, with a pipe between them. It does this
if the name s is at most 255 bytes long and s/log exists. (In versions 0.70 and below, it does this if s is sticky.) svscan needs two free
descriptors for each pipe.
Every five seconds, svscan checks for subdirectories again. If it sees a new subdirectory, it starts a new supervise(8) process. If it sees
an old subdirectory where a supervise(8) process has exited, it restarts the supervise(8) process. In the log case it reuses the same pipe
so that no data is lost.
svscan is designed to run forever. If it has trouble creating a pipe or running supervise(8), it prints a message to stderr; it will try
again five seconds later.
If svscan is given a command-line argument directory, it switches to that directory when it starts.
SEE ALSO
supervise(8), svc(8), svok(8), svstat(8), svscanboot(8), readproctitle(8), fghack(8), pgrphack(8), multilog(8), tai64n(8), tai64nlocal(8),
setuidgid(8), envuidgid(8), envdir(8), softlimit(8), setlock(8)
http://cr.yp.to/daemontools.html
svscan(8)