Richard Suchenwirth 2008-01-23 - Here is a little "application server" that waits for the existence of a specified file, reads it, deletes it, and executes its contents, line by line.
It can be useful to trigger some action on a remote computer to whose file system you have write access, so you can send "orders" by writing to the magic file...
No warranties, currently Windows only (use sh -c for Linux). Silly little example:
Start:
filewait hello > hello.log
Send an order:
$ echo > hello df -k .
After some seconds, the last lines of hello.log are (in my case)
2008-01-23T14:58:18 hello: 1 > df -k . 2008-01-23T14:58:23< 0 Filesystem 1k-blocks Used Available Use% Mounted on d: 156288320 154001928 2286392 99% /
#!/usr/bin/env tclsh
set usage {
filewait.tcl -- wait for a specified file, execute its contents
Example: filewait.tcl mycmd.txt > mycmd.log
The program deletes the waited-for file and keeps waiting.
}
proc main argv {
if {[llength $argv] != 1} {puts stderr $::usage; exit 1}
set ::waitfile [lindex $argv 0]
puts stderr "waiting for $::waitfile, Ctrl-C to terminate..."
every 1000 {
if {[file exists $waitfile]} {
set f [open $waitfile]
set content [read $f]
close $f
file delete $waitfile
set lineno 0
foreach line [split $content \n] {
if {[string trim $line] eq ""} continue
puts "[timestamp] $waitfile: [incr lineno] > $line"
set rc [catch {exec cmd /c $line} res]
puts "[timestamp]< $rc $res"
flush stdout
}
}
}
vwait forever
}
proc every {ms body} {uplevel \#0 $body; after $ms [info level 0]}
proc timestamp {} {clock format [clock seconds] -format %Y-%m-%dT%H:%M:%S}
main $argv