AJB which - A utility that almost works like the Unix which, but it works in Windows as well. The difference: if it doesn't find the file, it just returns null. I did this because it makes it easier to work with in programs. Unix returns something like: which: no "filename" in /bin /usr/bin /usr/local/bin ...
Also, if anyone has a Mac and knows what delimiter is used in ::env(PATH), could you please post the line to add to the opening switch statement so that this can be truly cross-platform? Thanks.
proc which {filename} {
switch $::tcl_platform(platform) {
windows {set dirlist [split $::env(PATH) \;]}
default {set dirlist [split $::env(PATH) :]}
}
foreach dir $dirlist {
set fullname [file join $dir $filename]
if {[file exists $fullname] && [file executable $fullname]} {
return $fullname
}
}
return ""
}LES: The idea above could also be slightly improved with the ability to detect common extensions in Windows, even if they're not provided in the argument:
proc which {filename} {
switch $::tcl_platform(platform) {
windows { set dirlist [split $::env(PATH) \;] }
default { set dirlist [split $::env(PATH) :] }
}
foreach dir $dirlist {
foreach ext {"" .exe .dll .com .bat} {
set fullname [file join $dir "$filename$ext"]
if { [file exists $fullname] && [file executable $fullname] } {
return $fullname
}
}
}
return ""
}And it could be improved further if the results were sent to a list instead of calling a return at the very sight of the first match. There might be more than one match.
AJB Thanks for the idea, I don't use Windows very often, and therefore I forgot that you can call binaries without the fullname. This should take care of the list. I did not do this because the "which" in Linux doesn't. Also, I wrote this to find binaries, and with other scripts' library dependencies, from a running Linux system to copy onto a flash drive. Essentially, a script to build a working bootable linux flash chip from a running Linux system. Therefore, the list would have made the rest of my programming difficult. I guess I was thinking in terms of a script to use as a building block to create adaptability in other programs.
proc which {filename} {
set list retlist
switch $::tcl_platform(platform) {
windows { set dirlist [split $::env(PATH) \;] }
default { set dirlist [split $::env(PATH) :] }
}
foreach dir $dirlist {
foreach ext {"" .exe .dll .com .bat} {
set fullname [file join $dir "$filename$ext"]
if { [file exists $fullname] && [file executable $fullname] } {
lappend retlist $fullname
}
}
}
if {[info exists retlist]} {return $retlist} {return ""}
}LES: Actually, I think this script/snippet only makes sense in Windows. In Unix, I'd rather just use the real McCoy:
exec which command
... and still, only because you can't expect to find Cygwin in most Windows machines.
SRIV Half of my embedded linux systems don't have which. The goal of this Tcl-coded which is to provide cross platform operation in a consistent manner. Personally, I only exec a binary as a last resort. Fewer dependencies make for a more robust app.
LV I hope that, instead of that exec, one checks first to see if which command returns a path, before just arbitrarily executing it...
JH tkcon has a more elaborate which that goes beyond executables to also give info on internal Tcl stuff, extracted here:
## which - tells you where a command is found, requires what
# ARGS: cmd - command name
# Returns: where command is found (internal / external / unknown)
##
proc which cmd {
## This tries to auto-load a command if not recognized
set types [uplevel 1 [list what $cmd 1]]
if {[llength $types]} {
set out {}
foreach type $types {
switch -- $type {
alias { set res "$cmd: aliased to [alias $cmd]" }
procedure { set res "$cmd: procedure" }
command { set res "$cmd: internal command" }
executable { lappend out [auto_execok $cmd] }
variable { lappend out "$cmd: $type" }
}
if {[info exists res]} {
global auto_index
if {[info exists auto_index($cmd)]} {
## This tells you where the command MIGHT have come from -
## not true if the command was redefined interactively or
## existed before it had to be auto_loaded. This is just
## provided as a hint at where it MAY have come from
append res " ($auto_index($cmd))"
}
lappend out $res
unset res
}
}
return [join $out \n]
} else {
return -code error "$cmd: command not found"
}
}
## what - tells you what a string is recognized as, used by which
# ARGS: str - string to id
# Returns: id types of command as list
##
proc what {str {autoload 0}} {
set types {}
if {[llength [info commands $str]] || ($autoload && \
[auto_load $str] && [llength [info commands $str]])} {
if {[lsearch -exact [interp aliases] $str] > -1} {
lappend types "alias"
} elseif {
[llength [info procs $str]] ||
([string match *::* $str] &&
[llength [namespace eval [namespace qualifier $str] \
info procs [namespace tail $str]]])
} {
lappend types "procedure"
} else {
lappend types "command"
}
}
if {[llength [uplevel 1 info vars $str]]} {
upvar 1 $str var
if {[array exists var]} {
lappend types array variable
} else {
lappend types scalar variable
}
}
if {[file isdirectory $str]} {
lappend types "directory"
}
if {[file isfile $str]} {
lappend types "file"
}
if {[llength [info commands winfo]] && [winfo exists $str]} {
lappend types "widget"
}
if {[string compare {} [auto_execok $str]]} {
lappend types "executable"
}
return $types
}escargo 22 Mar 2004 - There is a Linux command related to which, which is whereis, which also helps indentify the locations of executables.
LES on Apr 11, 2004: you may have unexpected results running this script in Cygwin. Read my comment in the Cygwin page.
Also, remember that Windows holds an alternative "PATH variable" in this Registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths
Wait a minute! What is wrong with auto_execok?!!
Umm - auto_execok isn't exactly the same. which is supposed to return a path for an item, or an empty string. auto_execok is documented to return arguments needed to pass for the execution of a built in or an external command...