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copied!<p>You can use <code>addTaskCallback</code> as follows to create a log of each top level execution.</p> <pre><code>.log <- data.frame(time=character(0), expr=character(0)) .logger <- function(expr, value, ok, visible) { # formals described in ?addTaskCallback time <- as.character(Sys.time()) expr <- deparse(expr) .log <<- rbind(.log, data.frame(time, expr)) return(TRUE) # required of task callback functions } .save.log <- function() { if (exists('.logger')) write.csv(.log, 'log.csv') } addTaskCallback(.logger) x <- 1:10 y <- mean(x) .save.log() .log # time expr # 1 2013-06-27 12:01:45.837 addTaskCallback(.logger) # 2 2013-06-27 12:01:45.866 x <- 1:10 # 3 2013-06-27 12:01:45.876 y <- mean(x) # 4 2013-06-27 12:01:45.900 .save.log() </code></pre> <p>Of course instead of committing the cardinal sin of growing a <code>data.frame</code> row-wise, as I have here, you could just leave a connection open and write directly to file, closing the connection with <code>on.exit</code>.</p> <p>And if you want to be tidy about it, you can pack the logging setup into a function pretty nicely.</p> <pre><code>.log <- function() { .logger <<- local({ log <- data.frame(time=character(0), expr=character(0)) function(expr, value, ok, visible) { time <- as.character(Sys.time()) expr <- deparse(expr) log <<- rbind(log, data.frame(time, expr)) return(TRUE) } }) invisible(addTaskCallback(.logger)) } .save.log <- function() { if (exists('.logger')) write.csv(environment(.logger)$log, 'log.csv') } .log() x <- 1:10 y <- mean(x) .save.log() </code></pre>

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