Grep comes with a lot of options which allow us to perform various search-related actions on files. It is a command line tool used in UNIX and Linux systems to search a specified pattern in a file or group of files. These are tools that any new administrator should become familiar with.Grep stands for Globally Search For Regular Expression and Print out. The grep command is a particularly versatile tool that can be used with redirecting, searching multiple patterns, regular expressions, and more. As mentioned in the previous blog, you can use the man command to get more information. These two commands have many different options and can do different things. You can also use the up and down arrows to move a single line in the corresponding direction. The space bar will move to the next page, the b key will go back a page, and the q key will quit and take you back to the regular terminal screen. After hitting enter, the results will fill your screen then pause. The pipe is the vertical line character, and it “pipes” the first command results into the less command. To do this, you’ll use the pipe: grep -i -C5 ‘error’ junglediskserver.log | less. Here, you can use the less command, which will output results screen by screen, and you control when the next section outputs. How can anyone read that quickly? Fortunately, you don’t have to. Now you may notice, if you have line after line of output, it all just scrolls past the terminal screen until it reaches the end. Too much output? “Less” of a problem than you think. The syntax is the same, and outputs “n” number of lines before or after the search pattern. Two options similar to that are -B and -A, for before and after. With the Jungle Disk log file, this option can be helpful to get more error detail and information about what happened before the error occured. For example, grep -i -C5 ‘error’ junglediskserver.log is not only case insensitive, but it will also output the five lines before and after the search pattern “error”. The “n” is an integer that will show that number of lines before and after the search pattern, giving you “context”. In the previous example, if you’re unsure of the letter case (such as “Error” versus “error”), you can use grep -i ‘error’ junglediskserver.log, and all letter case variations of “error” will output.Īnother useful option is -C, which stands for context. Search patterns, like file names, are case sensitive. For example, to search for the word “error” in the log file, you would enter grep ‘error’ junglediskserver.log, and all lines that contain”error” will output to the screen. For searching files, the command syntax you use is grep, where “pattern” is what you want to search for. Next, we’ll use the versatile grep command. For any users new to Linux, that just means changing directory to get into the folder where the log file resides. If your backup report emails or the admin Control Panel online tells you your backups have errors, and you want to get more detail from the log, how would you do this? First, we’ll go into the directory with the log by using the command cd /var/log. CENTOS GREP USAGE INSTALLOn Linux machines without a GUI, you’d install Jungle Disk Server edition, whose log file is named junglediskserver.log. On Linux machines, the verbose log will reside in the /var/log directory. As a side note, when enabling verbose logs, you may also want to click the the “Clear” button to get rid of old logs. When you notice issues with your Jungle Disk backups, the first thing you’ll want to do is enable verbose logs (), as this will give you more detailed information. In this post, I’ll be using Jungle Disk logs as an example. When troubleshooting issues, administrators sometimes need to search logs to pinpoint warnings or errors. This is really helpful for searching log files, which can grow very large and may contain a great deal of information you don’t need. Now, I’d like to take a look at searching files for specific terms or phrases. Previously, I wrote a blog post about Linux commands to solve space issues.
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