io.popen - how to wait for process to finish in Lua?
33,218
If you are using standard Lua your code looks a bit odd. I am not completely sure about io.popen
semantics regarding timeouts or platform dependencies, but the following works at least on my machine.
local file = assert(io.popen('/bin/ls -la', 'r'))
local output = file:read('*all')
file:close()
print(output) -- > Prints the output of the command.
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Author by
Chet
Updated on July 09, 2022Comments
-
Chet over 1 year
I have to use
io.popen
in Lua to run an executable which takes a command line argument. How to wait for a process to finish in the Lua so that expected output can be captured?local command = "C:\Program Files\XYZ.exe /all" hOutput = io.popen(command) print(string.format(""%s", hOutput))
Suppose the executable is XYZ.exe which needs to be called with command line argument
/all
.Once
io.popen(command)
gets executed, the process will return some string which needs to be printed.My code snippet:
function capture(cmd, raw) local f = assert(io.popen(cmd, 'r')) -- wait(10000); local s = assert(f:read('*a')) Print(string.format("String: %s",s )) f:close() if raw then return s end s = string.gsub(s, '^%s+', '') s = string.gsub(s, '%s+$', '') s = string.gsub(s, '[\n\r]+', ' ') return s end local command = capture("C:\Tester.exe /all")
Your help will be appreciated.
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rubo77 over 4 yearscan you explain, why you need the
assert
around? -
ponzao over 4 years@rubo77, I haven't used Lua in a while, but based on a quick test I don't think the
assert
is at all useful in this case asio.popen
seems to return an object even when there is an error.