tail

问题 I am trying to find a Unix command (combination, maybe) on how to continuously display a file of its last several lines of contents. But during this displaying, I want some of the top lines are always displayed on the screen top when the rolling contents reach the screen top. Is that possible? (1) Suppose I have file, "job.sta", the first 2 lines are: job name, John's job on 2013-Jan-30,... Tab1, Tab2, Tab3 0, 1, 2, 1, 90, 89 2, 89, 23 ... (2) This file is on its running, its contents are

问题 I am trying to find a Unix command (combination, maybe) on how to continuously display a file of its last several lines of contents. But during this displaying, I want some of the top lines are always displayed on the screen top when the rolling contents reach the screen top. Is that possible? (1) Suppose I have file, "job.sta", the first 2 lines are: job name, John's job on 2013-Jan-30,... Tab1, Tab2, Tab3 0, 1, 2, 1, 90, 89 2, 89, 23 ... (2) This file is on its running, its contents are

问题 I wrote a method to calculate the maximum depth of a binary tree. I would like to write a tail recursive method. I thought of using lists, but I didn't find solutions This is my method that is not tail recursive: def depth: Int = { def iter(f: FormulaWff): Int = f match { case Var(_) => 0 case Not(e1) => 1 + iter(e1) case And(e1, e2) => 1 + Math.max(iter(e1), iter(e2)) case Or(e1, e2) => 1 + Math.max(iter(e1), iter(e2)) case Implies(e1, e2) => 1 + Math.max(iter(e1), iter(e2)) } iter(this) }

问题 Im trying to implement the simple tail -f linux command in java. Here is my code. try { // position within the file File file = new File("/home/curuk/monitored/log.txt"); RandomAccessFile raFile = new RandomAccessFile(file, "r"); long last = file.lastModified(); // The last time the file was checked for changes long position = file.length(); while (true) { if (file.lastModified() > last) { last = file.lastModified(); readFromFile(raFile, (int) position, (int) (file.length() - position));

问题 I have the following dataframe dat , which presents a row-specific number of NAs at the beginning of some of its rows: dat <- as.data.frame(rbind(c(NA,NA,1,3,5,NA,NA,NA), c(NA,1:3,6:8,NA), c(1:7,NA))) dat # V1 V2 V3 V4 V5 V6 V7 V8 # NA NA 1 3 5 NA NA NA # NA 1 2 3 6 7 8 NA # 1 NA 2 3 4 5 6 NA My aim is to delete all the NAs at the beginning of each row and to left shift the row values (adding NAs at the end of the shifted rows accordingly, in order to keep their length constant). The

问题 i'm trying to build a shell script to monitor some log files. I'm using a command like this: tail -f /var/somelog | grep --line-buffered " some test and p l a c e h o l d e r" | cut -f 3,4,14 -d " " the log file is like: some test and p l a c e h o l d e r 3 some test and p l a c e h o l d e r 4 some test and p l a c e h o l d e r 5 some test and p l a c e h o l d e r 6 and so on.. My issue is that the output of the command does not display the last line some test and p l a c e h o l d e r 6

问题 i'm trying to build a shell script to monitor some log files. I'm using a command like this: tail -f /var/somelog | grep --line-buffered " some test and p l a c e h o l d e r" | cut -f 3,4,14 -d " " the log file is like: some test and p l a c e h o l d e r 3 some test and p l a c e h o l d e r 4 some test and p l a c e h o l d e r 5 some test and p l a c e h o l d e r 6 and so on.. My issue is that the output of the command does not display the last line some test and p l a c e h o l d e r 6

问题 I have a data frame containing a time series with two time stamp columns, d$day and d$time , and say, for simplicity, one measured variable d$val1 . Suppose I want to examine the situation at the close of each day's experiment, i.e. the last measurement, if it exists. (Not every day has a measurement, and measurements can be taken at different times each day.) I would like to be able to aggregate by day and use some sort of last() or tail() function on time to pull back the corresponding val

问题 I have implemented my own dynamic-memory version of getline function: char * fgetline(FILE * f) Starts with 30 character buffer and when the buffer is full allocate a new one copy the contents and free the old buffer. When we get EOF or \n we return from the function. I want to use this function to implement a version of the program tail. Input comes from stdin, output goes to stdout. If the first argument begins with - , everything after the - is the number of lines to print. The default

问题 I'm monitoring a log file. Each line has the following format: 2012 5 29 14 20 438.815 872.737 -1.89976 -0.55156 8.68749 -0.497848 -0.54559 0 0 6 00 0 0 0 0 0 0 0 0 80 9 0 0 10 0 0 0 8 00 9 0 0 0 0 0 0 2 41 84 0 0 0 1 0 As you can see, each value is delimited by a tab. How can I write a Perl script to take each new line of data (the log file is updated every ten minutes) and insert this data into a MySQL database? I'd like to do as much of this as possible on the command line. If I do tail -f