as.POSIXct("Tue Aug 18 2020 08:45:02 GMT+0000 (Coordinated Universal Time)", tx="UTC", format = "%a %b %d %Y %H:%M:%OS")
[1] "2020-07-13 08:24:03 BST"
same output with GMT instead of UTC set as the timezone
as.POSIXct("Tue Aug 18 2020 08:45:02 GMT+0000 (Coordinated Universal Time)", tx="GMT", format = "%a %b %d %Y %H:%M:%OS")
[1] "2020-07-13 08:24:03 BST"
for reference I'm doing this in Rstudio
The option for timezone is "tz" not "tx". This works as expected:
> as.POSIXct("Tue Aug 18 2020 08:45:02 GMT+0000 (Coordinated Universal Time)", tz="UTC", format = "%a %b %d %Y %H:%M:%OS")
[1] "2020-08-18 08:45:02 UTC"