![]() Much like the -v flag, the -L flag is the opposite of -l. *įinding filenames that don't contain the search term The -l flag will accomplish this without needing to call any awk or cut commands. If you want to find a string in multiple files, but only want to know the filenames of those files (to run in a for loop maybe?). Though this feature isn't available on older implementations of grep, most up to date systems will have this feature. The grep command can be used recursively as well. There is no need for complicated find commands. If you need to search through multiple files like the above example, but the files are in separate directories. Searching through multiple files recursively Sometimes, when you need to search for “something” you need to search multiple files, this is as simple as giving grep multiple files to search. I use this frequently when writing bash scripts to check if something is true or false. One of my most common usages of grep is counting the number of times a search string is found. The above command will remove all files in the current directory except the ones with. While I've used -v with grep in many use cases one that pops up is performing multiple rm commands through a for loop or xargs. Normally grep will return the string that you are searching for, when given the -v flag grep will omit the searched string and return everything else. The grep command is a powerful search tool, below are some examples of grep commands that I have found incredibly useful in daily tasks. The previous method requires both the cat and grep command to run which takes longer to run and uses more system resources (even if they are minor resources, it's less efficient). Stop Doing This: $ cat file.log | grep "something"ĭo This More: $ grep "something" file.logĪside from saving yourself some typing, this method is preferred because you only have to read and search the file through one process. Because of this some Linux users just assume that grep can only be used with stdin it's ok, I was one of those too!īefore I continue with some grep tricks I want to clarify the basic grep usage. logsearch.sh localhost /var/tmp/logXray autonda /var/log 60m 'fatal_P_error_P_critical_P_failure_P_warning' '.The grep command is a command that most Linux users learn early on, and many times they learn to use it via pipes (stdin). Solution to the Original Poster's Issue: Scan for Multiple strings in multiple log files. logsearch.sh localhost /var/tmp/logXray autonda /var/log/messages 60m 'can.*t.*open_P_ntpd.*stat' '.' 1 2 blahblahA -ndfoundmul When using '-ndfoundmul', you'll get an output similar to. If you just want to see the total count of each pattern found, simply replace '-ndshow' with '-ndfoundmul'. The log option -ndshow - This is the parameter you want to use if you wish to output the entries from the logs found matching the pattern(s) you specified.It records stats about the log file(s) you're monitoring under /var/tmp/logXray The tag - this is the second to last argument you have to supply.The strings(s)/pattern(s) you want to watch for.do not monitor or discover any log file that has a timestamp over 60 minutes The age a log file must be for it to be monitored.i.e.The log file or log directory to be monitored.When using this script, the parameters you'll be changing frequently are: If you dont wish to type "_P_", you can just substitute the _P_ with "|". The _P_ means OR - It replaces the pipe "|" symbol because it is less likely you'll have to search for a string containing "_P_". logsearch.sh localhost /var/tmp/logXray autonda /var/log 60m 'can.*t.*open_P_ntpd.*stat' '.' 1 2 multi_err_multi_logCheck -ndshow Scenario 3: Monitor Single/Multiple strings in Multiple log files. logsearch.sh localhost /var/tmp/logXray autonda /var/log/messages 60m 'can.*t.*open_P_ntpd.*stat' '.' 1 2 multi_errCheck -ndshow Scenario 2: Monitor MULTIPLE strings in just ONE log file. logsearch.sh localhost /var/tmp/logXray autonda /var/log/messages 60m 'can.*t.*open' '.' 1 2 single_errCheck -ndshow Scenario 1: Monitor ONE string in just ONE log file. Nevertheless, it is done and ready and can be downloaded from the following link: But I recently had to do this and it was quite painful. And yes, it certainly needed to be scripted if you're going to search for multiple strings in multiple different logs at the same time.
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