I need to write a PowerShell script, that allows the user to pass a txt file, that contains the standard information you'd get from a
Get-Process > proc.txt
statement as a parameter and then compare the processes in the file with the currently running ones. I then need to display Id, Name, Starting time and running time for every process, that isn't in the txt file and therefore a new process.
To give you a general idea of how I would approach this: I would
Extract only the names of the processes from the txt file into a variable (v1).
Save only the names of all the currently running processes in a variable (v2).
Compare the 2 variables(v1, v2) and write the processes that are not in the txt file (the new ones) into yet another variable (v3).
Get the process ID, the starting time and the running time for each process name in v3 and output all of that (including name) into the console and in a new file.
First of all, how can I only read the names of the processes from the txt file? I tried to find it on the internet but had no luck.
Secondly how can I save only the new processes in a variable and not all the differences (e.g. processes that are in the file but currently not running).
As far as I know,
Compare-Object
returns all the differences.
Thirdly how can I get the remaining process information I want from all the process names in v3?
And finally how can I then neatly combine ID, starting time, running time and the names from v3 in one file?
I'm pretty much a beginner at PowerShell programming, I'm pretty sure my 4 step approach posted above is most likely wrong and therefore appreciate any help I can get.
Related
I have many files that are extracted into .txt with a batch file. But they don't have the headers. I've read that a possible solution from here that is to add to a .txt with the headers the exported rows.
With this:
echo. >> titles.txt
type data.txt >> titles.txt
This takes a lot of time and is not efficient, since it is adding the big file to the file with the text.
Another possible solution is to add to the SQL query the titles hardcoded, but this will change the type of the columns (is they are numeric they will be changed to varchar).
Is there a way to insert in the first row of the data txt the headers and not doing vice-versa?
I might be wrong, but as far as I am informed (and as far as I know from earlier experiments in doing as described): No, it is not possible! The mentioned Tasks are acting on the file sequentially. You can either open a file for reading, writing or appending. If you open the titles.txt file for writing, it is overwritten - and with this empty. If you open it for appending, it can only append to the end of the file - so you can only write the data after the Header... the only way it might work - but which is pretty nasty - is to append the title to the end of the file and during later processing (e.g. xls or whatever) Resort the rows and put the last one to the beginning. But as mentioned: nasty and not really the way to go.
If the number of files to process is a bigger problem than any individual file size, switching from bcp to sqlcmd might help.
I'm writing a program/utility in C to find (and then move to a new directory) the files in the current directory that have been modified after the last time the utility was run.
What I'm trying to find out is if there is a way to find the last time this utility ran. Or alternatively, a way to store the time in the program (so as to compare the last stored time against the current time, and then update the "last time" variable to current time).
As I type this it occurs to me that I could write the time to a file (overwriting the single entry as the utility is run) and retrieve the value from the file in the program, although I don't know if this would be the best approach.
you can make a class contains info and serialize it to a text file , it's more easy to access and can store multiple values,
then to store new values first delete file and then create file again.
another approach could be a register key containing information.
hope it would be useful ;)
You can use the last access time from the filesystem (In GNU/linux you can use ls -lu to see last access time).
This is not a portable solution because it depends on filesystem and filesystem settings (see JoachimPileborg edit below)
Moreover look at this question to get last acces time in C (use atime instead of mtime).
I have a program which logs its activity.
I want to implement a log file mechanism to keep the log file under a certain size, lets say 10 MB.
The log file itself just holds commands the program executed; those commands are variable length.
Right now, the program runs on a windows environment, but I'm likely to port it to UNIX soon.
I've came up with two methods for managing the log files:
1. Keep multiple files of lower size, and if the new command exceeds the current file length, truncate the oldest file to zero size, and start writing there.
2. Keep a header in the file, which holds metadata regarding the first command in the file, and the next place to write to in the file. Also I think, each command should hold metadata about it's length this way.
My questions are as follows:
In terms of efficiency which of these methods would you use, and why?
Is there a unix command / function to this easily?
Thanks a lot for your help,
Nihil.
On UNIX/Linux platforms there's a logrotate program that manages logfiles. Details can be found for example here:
http://linuxcommand.org/man_pages/logrotate8.html
I've got a service which runs all the time and also keeps a log file. It basically adds new lines to the log file every few seconds. I'm written a small file which reads these lines and then parses them to various actions. The question I have is how can I delete the lines which I have already parsed from the log file without disrupting the writing of the log file by the service?
Usually when I need to delete a line in a file then I open the original one and a temporary one and then I just write all the lines to the temp file except the original which I want to delete. Obviously this method will not word here.
So how do I go about deleting them ?
In most commonly used file systems you can't delete a line from the beginning of a file without rewriting the entire file. I'd suggest instead of one large file, use lots of small files and rotate them for example once per day. The old files are deleted when you no longer need them.
Can't be done, unfortunately, without rewriting the file, either in-place or as a separate file.
One thing you may want to look at is to maintain a pointer in another file, specifying the position of the first unprocessed line.
Then your process simply opens the file and seeks to that location, processes some lines, then updates the pointer.
You'll still need to roll over the files at some point lest they continue to grow forever.
I'm not sure, but I'm thinking in this way:
New Line is a char, so you must delete chars for that line + New Line char
By the way, "moving" all characters back (to overwrite the old line), is like copying each character in a different position, and removing them from their old position
So no, I don't think you can just delete a line, you should rewrite all the file.
You can't, that just isn't how files work.
It sounds like you need some sort of message logging service / library that your program could connect to in order to log messages, which could then hide the underlying details of file opening / closing etc.
If each log line has a unique identifier (or even just line number), you could simply store in your log-parsing the identifier until which you got parsing. That way you don't have to change anything in the log file.
If the log file then starts to get too big, you could switch to a new one each day (for example).
just had a general question about how to approach a certain problem I'm facing. I'm fairly new to C so bear with me here. Say I have a folder with 1000+ text files, the files are not named in any kind of numbered order, but they are alphabetical. For my problem I have files of stock data, each file is named after the company's respective ticker. I want to write a program that will open each file, read the data find the historical low and compare it to the current price and calculate the percent change, and then print it. Searching and calculating are not a problem, the problem is getting the program to go through and open each file. The only way I can see to attack this is to create a text file containing all of the ticker symbols, having the program read that into an array and then run a loop that first opens the first filename in the array, perform the calculations, print the output, close the file, then loop back around moving to the second element (the next ticker symbol) in the array. This would be fairly simple to set up (I think) but I'd really like to avoid typing out over a thousand file names into a text file. Is there a better way to approach this? Not really asking for code ( unless there is some amazing function in c that will do this for me ;) ), just some advice from more experienced C programmers.
Thanks :)
Edit: This is on Linux, sorry I forgot to metion that!
Under Linux/Unix (BSD, OS X, POSIX, etc.) you can use opendir / readdir to go through the directory structure. No need to generate static files that need to be updated, when the file system has the information you want. If you only want a sub-set of stocks at a given time, then using glob would be quicker, there is also scandir.
I don't know what Win32 (Windows / Platform SDK) functions are called, if you are developing using Visual C++ as your C compiler. Searching MSDN Library should help you.
Assuming you're running on linux...
ls /path/to/text/files > names.txt
is exactly what you want.
opendir(); on linux.
http://linux.die.net/man/3/opendir
Exemple :
http://snippets.dzone.com/posts/show/5734
In pseudo code it would look like this, I cannot define the code as I'm not 100% sure if this is the correct approach...
for each directory entry
scan the filename
extract the ticker name from the filename
open the file
read the data
create a record consisting of the filename, data.....
close the file
add the record to a list/array...
> sort the list/array into alphabetical order based on
the ticker name in the filename...
You could vary it slightly if you wish, scan the filenames in the directory entries and sort them first by building a record with the filenames first, then go back to the start of the list/array and open each one individually reading the data and putting it into the record then....
Hope this helps,
best regards,
Tom.
There are no functions in standard C that have any notion of a "directory". You will need to use some kind of platform-specific function to do this. For some examples, take a look at this post from Cprogrammnig.com.
Personally, I prefer using the opendir()/readdir() approach as shown in the second example. It works natively under Linux and also on Windows if you are using Cygwin.
Approach 1) I would just have a specific directory in which I have ONLY these files containing the ticker data and nothing else. I would then use the C readdir API to list all files in the directory and iterate over each one performing the data processing that you require. Which ticker the file applies to is determined only by the filename.
Pros: Easy to code
Cons: It really depends where the files are stored and where they come from.
Approach 2) Change the file format so the ticker files start with a magic code identifying that this is a ticker file, and a string containing the name. As before use readdir to iterate through all files in the folder and open each file, ensure that the magic number is set and read the ticker name from the file, and process the data as before
Pros: More flexible than before. Filename needn't reflect name of ticker
Cons: Harder to code, file format may be fixed.
but I'd really like to avoid typing out over a thousand file names into a text file. Is there a better way to approach this?
I have solved the exact same problem a while back, albeit for personal uses :)
What I did was to use the OS shell commands to generate a list of those files and redirected the output to a text file and had my program run through them.
On UNIX, there's the handy glob function:
glob_t results;
memset(&results, 0, sizeof(results));
glob("*.txt", 0, NULL, &results);
for (i = 0; i < results.gl_pathc; i++)
printf("%s\n", results.gl_pathv[i]);
globfree(&results);
On Linux or a related system, you could use the fts library. It's designed for traversing file hierarchies: man fts,
or even something as simple as readdir
If on Windows, you can use their Directory Management API's. More specifically, the FindFirstFile function, used with wildcards, in conjunction with FindNextFile