Is there way to grep based on the result of a previous grep?

Is there way to grep based on the result of a previous grep?

Is there a way to perform a grep based on the results of a previous grep, rather than just piping multiple greps into each other. For example, say I have the log file output below: To begin with, I’d like to grep the whole log file file to see if “xyz occured” is present.

How to run grep on different file types?

$ grep “Hello” * grep: Test: Is a directory test.cc:Hello World! test.h:Hello World! test.txt:Hello World! This command runs grep with no options, the pattern “Hello,” and runs it on every file in the local directory. With files that match the PATTERN, it will output the file’s name, followed by the line that contains the matching text.

Where can I find the output of grep?

The output will return results from all files the grep command found in the /var/log/ directory and its subdirectories. In this tutorial, you learned how to use grep to search multiple words or string patterns in a file.

How to redirect grep to an output file?

grep -n “test” * | grep -v “mytest” > output-file will match all the lines that have the string “test” except the lines that match the string “mytest” (that’s the switch -v) – and will redirect the result to an output file. Redirection of program output is performed by the shell.

What happens if the outer grep returns multiple IDs?

If the outer grep returns multiple ID numbers, then the inner grep will only search the first ID number and error out on the others. The thing I like about this method is if you wanted to you could write the output to a file for each status code.

Is there a way to avoid grep-V grep?

A good trick to avoid grep -v grep is this: ps -ef | grep ‘[b]ar’. That regular expression only matches the string “bar”. However in the ps output, the string “bar” does not appear with the grep process.

What does grep do when output is suppressed?

When some output is suppressed, grep follows any output with a one-line message saying that a binary file matches. If TYPE is without-match, when grep discovers null input binary data it assumes that the rest of the file does not match; this is equivalent to the -I option.

How can I grep the results of find using exec and still?

If you want each run of grep to produce output to a different file, run a shell to compute the output file name and perform the redirection. For the record, grep has –include and –exclude arguments that you can use to filter the files it searches:

What is a list of patterns in grep?

It’s just a list of patterns like the “1\\.2\\.3\\.4.*Has exploded” part I am passing, in a loop, so I can’t pass “-v” for example. I am confused trying to do the inverse of the above, and NOT match lines with a certain IP address and error so “!1.2.3.4.*Has exploded” will match syslog lines for anything other than 1.2.3.4 telling me it has exploded.

How to avoid stack overflow with grep regex?

If you need to “match A but not B” you usually use pipes: Try this. It uses negative lookbehind to ignore the line if it is preceeded by 1.2.3.4. Hope that helps! Thanks for contributing an answer to Stack Overflow!

Can a xargs be used as a grep?

You’re almost there. But while xargs can sometimes be used to do what you want (depending on how the next command takes its arguments), you aren’t actually using it to grep for the ID you just extracted. What you need to do is take the output of the first grep (containing the ID code) and use that in the next grep’s expression.