I have a process that is continually writing new files to a directory. When the current file reaches a certain size, it creates a new one with the timestamp. Like rolling log files, for example.
When the process closes the current file (A) and creates a new one, I would like to move A to a new directory for processing. I'm not sure of the best way to do this...
I wrote a bash script that runs every few minutes, lists all the files in the dir sorted by time, and moves all but the most recent. This works, but I can't help but feel like there is a better way, something more event-driven. I was looking at using inotifywait and capturing the CLOSE_WRITE,CLOSE event for the file ...
Any suggestions?
Thanks!
Found a better way. Using incron:
http://inotify.aiken.cz/?section=incron&page=why&lang=en
Related
I a series of applications on Linux systems that I need to basically constantly 'stream' out or even just 'tail' out but the challenge is the filenames are constantly rolling and changing.
The are all date encoded (dates being in different formats) and each then have different incremented formats.
Most of them start with one and increase, but one doesn't have an extension and then adds an extension past the first file and the other increments a number but once hitting 99 rolls to increment a alpha and returns the numeric to 01 and then up again as it rolls so quickly.
I just have the OS level shell scripting, OS command line utilities, and perl available to me to handle this situation for another application to pickup and read these logs.
The new files are always created right when it starts writing to the new file and groups of different logs (some I am reading some I am not) are being written to the same directory so I cannot just pickup anything hitting the directory.
If I simply 'tail -n 1000000 -f |' them today this works fine for the reader application I am using until the file changes and I cannot setup file lists ranges within the reader application, but can pre-process them so they basically appear as a continuous stream to the reader vs. the reader directly invoking commands to read them. A simple Perl log reader like this also work fine for a static filename but not for dynamic ones. It is critical I don't re-process any logs lines and just capture new lines being written to the logs.
I admit I am not any form a Perl guru, and the best answers / clue I've been able to find so far is the use of Perl's Glob function to possibly do this but the examples I've found basically reprocess all of the files on each run then seem to stop.
Example File Names I am dealing with across multiple apps I am trying to handle..
appA_YYMMDD.log
appA_YYMMDD_0001.log
appA_YYMMDD_0002.log
WS01APPB_YYMMDD.log
WS02APPB_YYMMDD.log
WS03AppB_YYMMDD.log
APPCMMDD_A01.log
APPCMMDD_B01.log
YYYYMMDD_001_APPD.log
As denoted above the files do not have the same inode and simply monitoring the directory for change is not possible as a lot of things are written there. On the dev system it has more than 50 logs being written to the directory and thousands of files and I am only trying to retrieve 5. I am seeing if multitail can be made available to try that suggestion but it is not currently available and installing any additional RPMs in the environment is generally a multi-month battle.
ls -i
24792 APPA_180901.log
24805 APPA__180902.log
17011 APPA__180903.log
17072 APPA__180904.log
24644 APPA__180905.log
17081 APPA__180906.log
17115 APPA__180907.log
So really the root of what I am trying to do is simply a continuous stream regardless if the file name changes and not have to run the extract command repeatedly nor have big breaks in the data feed while some script figures out that the file being logged to has changed. I don't need to parse the contents (my other app does that).. Is there an easy way of handling this changing file name?
How about monitoring the log directory for changes with Linux inotify, e.g. Linux::inotify2? Then you could detect when new log files are created, stop reading from the old log file and start reading from the new log file.
Try tailswitch. I created this script to tail log files that are rotated daily and have YYYY-MM-DD on their names. To use this script, you just say:
% tailswitch '*.log'
The quoting prevents the shell from interpreting the glob pattern. The script will perform glob pattern from time to time to switch to a newer file based on its name.
I'm not an advanced user of Linux, but I'm looking for some simple script in bash which will be working in cron or any other way and in 5-10 minutes period time will be looking for new files, after new directory/files are already uploaded to the directory script will move new directory with files to other location.
I found inotify which can be a great solution for this, but the issue is how to go with it.
I've been using inotifywait to recognize that some filesystem change ocurred in certain path.
Take a look at:
http://linux.die.net/man/1/inotifywait
You can specify on what changes you are interested (delete, create, modify, etc.) and whether the script should output it or simply exit after change.
I've been using this tool in a way that my script was starting inotifywait and when it exists, do some action and restart inotifywait again.
Hope this helps.
Martin
Recently I was asked the following question in an interview.
Suppose I try to create a new file named myfile.txt in the /home/pavan directory.
It should automatically create myfileCopy.txt in the same directory.
A.txt then it automatically creates ACopy.txt,
B.txt then BCopy.txt in the same directory.
How can this be done using a script? I may know that this script should run in crontab.
Please don't use inotify-tools.
Can you explain why you want to do?
Tools like VIM can create a backup copy of a file you're working on automatically. Other tools like Dropbox (which works on Linux, Windows, and Mac) can version files, so it backs up all the copies of the file for the last 30 days.
You could do something by creating aliases to the tools you use for creating these file. You edit a file with the tools you tend to use, and the alias could create a copy before invoking a tool.
Otherwise, your choice is to use crontab to occasionally make backups.
Addendum
let me explain suppose i have directory /home/pavan now i create the file myfile.txt in that directory , immediately now i should automatically generate myfileCopy.txt file in the same folder
paven
There's no easy user tool that could do that. In fact, the way you stated it, it's not clear exactly what you want to do and why. Backups are done for two reasons:
To save an older version of the file in case I need to undo recent changes. In your scenario, I'm simply saving a new unchanged file.
To save a file in case of disaster. I want that file to be located elsewhere: On a different computer, maybe in a different physical location, or at least not on the same disk drive as my current file. In your case, you're making the backup in the same directory.
Tools like VIM can be set to automatically backup a file you're editing. This satisfy reason #1 stated above: To get back an older revision of the file. EMACs could create an infinite series of backups.
Tools like Dropbox create a backup of your file in a different location across the aether. This satisfies reason #2 which will keep the file incase of a disaster. Dropbox also versions files you save which also is reason #1.
Version control tools can also do both, if I remember to commit my changes. They store all changes in my file (reason #1) and can store this on a server in a remote location (reason #2).
I was thinking of crontab, but what would I backup? Backup any file that had been modified (reason #1), but that doesn't make too much sense if I'm storing it in the same directory. All I would have are duplicate copies of files. It would make sense to backup the previous version, but how would I get a simple crontab to know this? Do you want to keep the older version of a file, or only the original copy?
The only real way to do this is at the system level with tools that layer over the disk IO calls. For example, at one location, we used Netapps to create a $HOME/.snapshot directory that contained the way your directory looked every minute for an hour, every hour for a day, and every day for a month. If someone deleted a file or messed it up, there was a good chance that the version of the file exists somewhere in the $HOME/.snapshot directory.
On my Mac, I use a combination of Time Machine - which backs up the entire drive every hour, and gives me a snapshot of my drive that stretches back over a year and a half) and Dropbox which keeps my files stored in the main Dropbox server somewhere. I've been saved many times by that combination.
I now understand that this was an interview question. I'm not sure what was the position. Did the questioner want you to come up with a system wide way of implementing this, like a network tech position, or was this one of those brain leaks that someone comes up with at the spur of the moment when they interview someone, but were too drunk the night before to go over what they should really ask the applicant?
Did they want a whole discussion on what backups are for, and why backing up a file immediately upon creation in the same directory is a stupid idea non-optimal solution, or were they attempting to solve an issue that came up, but aren't technical enough to understand the real issue?
I need to move my web server directory to another server. I'd like to do it with a simple "scp -r destination:destdirectory". But in the meanwhile the directory will be filled with another stuff: so I'll take the old server down the time I need to move the newest file to the new one. How can I do an scp which is gonna write just the differences? So it'll take not much time, and I won't have to take the website down for too long!
Probably not at all, or just with pains. But if you have the possibility to use rsync, just do that. It automatically excludes files that haven't changed, and for changed files, it just transfers the differences.
How could I track changes of specific directory in UNIX? For example, I launch some utility which create some files during its execution. I want to know what exact files were created during one particular launch. Is there any simple way to get such information? Problem is that:
I cannot flush directory content after script execution
Files created with the name that has hash as a compound part. There is no possibility to get this hash from script for subsequent search.
There could be several scripts executed simultaneously, I do not want to see files created by another process in the same folder.
Please notice that I do not want to know whether directory has been changed as stated here, I need filenames which ideally could be grepped to match specific pattern.
You need to subscribe to file system change notifications.
You should use something like FAM, gamin, or inotify to detect when a file has been created, closed, etc.
You could use strace -f myscript to trace all system calls made by the script, and use grep to filter the system calls that create new files.
You could use the Linux Auditing System. Here is a howto link:
http://www.cyberciti.biz/tips/linux-audit-files-to-see-who-made-changes-to-a-file.html
You can use the script command to track the commands launched.