Is it possible to read the following from the local variable in Lua?
local t = os.execute("echo 'test'")
print(t)
I just want to achieve this: whenever os.execute returns any value, I would like to use it in Lua - for example echo 'test' will output test in the bash command line - is that possible to get the returned value (test in this case) to the Lua local variable?
You can use io.popen() instead. This returns a file handle you can use to read the output of the command. Something like the following may work:
local handle = io.popen(command)
local result = handle:read("*a")
handle:close()
Note that this will include the trailing newline (if any) that the command emits.
'popen' not supported.
os.execute() but redirect standard output to a known temporary file, and then read the temporary file afterwards.os.execute(command .. " >/tmp/foo") (where /tmp/foo is replaced by an actual somewhat unique path, however you want to calculate it).
function GetFiles(mask)
local files = {}
local tmpfile = '/tmp/stmp.txt'
os.execute('ls -1 '..mask..' > '..tmpfile)
local f = io.open(tmpfile)
if not f then return files end
local k = 1
for line in f:lines() do
files[k] = line
k = k + 1
end
f:close()
return files
end
If supported on your system, io.popen is better suited for this use-case than os.execute. The later only returns the exit status not the output.
-- runs command on a sub-process.
local handle = io.popen('cmd')
-- reads command output.
local output = handle:read('*a')
-- replaces any newline with a space
local format = output:gsub('[\n\r]', ' ')
Working example:
local handle = io.popen('date +"%T.%6N"')
local output = handle:read('*a')
local time = output:gsub('[\n\r]', ' ')
handle:close()
print(time .. 'DEBUG: Time recorded when this event happened.')
Lua's os.capture returns all standard output, thus it will be returned into that variable.
Example:
local result = os.capture("echo hallo")
print(result)
Printing:
hallo
os module. lua.org/manual/5.3/manual.html#6.9
Sorry, but this is impossible. If the echo programm exit with success it will return 0. This returncode is what the os.execute() function get and returned too.
if 0 == os.execute("echo 'test'") then
local t = "test"
end
This is a way to get what you want, i hope it helps you.
Another Tip for getting the return code of a function is the Lua reference. Lua-Reference/Tutorial
