Tools of the Trade: Quiz 3

The ???? command searches a specified file and returns all lines in the file containing a specified string.

Notice how the grep command is followed by two arguments. The first argument is the str_____ we're searching for; in this case, OS. The second argument is the name of the fi_______ we're searching through, updates.txt.

Piping is a Linux command that can be used for a variety of purposes. In a moment, we'll focus on how it can be used for fil_____. But first, let's talk about the general idea of piping. The piping command sends a standard output of one command as standard input into another command for further processing. It's represented by the vertical bar character. In our context, we can refer to this as the pipe character. Take a moment and imagine a physical pipe. Physical pipes have two ends. On one end, for example, water might enter the pipe from a hot water tank. Then, it travels through the pipe and comes out on the other end in a sink. Similarly, in Linux, piping also involves redirection. Output from one command is sent through the pipe and then is used on the other side of the pipe.

The pipe character ? is located in various places on a keyboard.

ls /home/analyst/reports | grep users returns the fi____ and dir_____ names in the reports directory that contain users. Before the pipe, ls indicates to list the names of the files and directories in reports. Then, it sends this output to the command after the pipe. In this case, grep users returns all of the file or directory names containing users from the input it received.

Note: Piping is a general form of redi_________ in Linux and can be used for multiple tasks other than filtering. You can think of piping as a general tool that you can use whenever you want the output of one command to become the in______ of another command.

The ???? command searches for directories and files that meet specified criteria. There’s a wide range of criteria that can be specified with ????. For example, you can search for files and directories that:

Contain a specific string in the name,

Are a certain file size, or

Were last modified within a certain time frame.

You might want to find all files in the projects directory that contain the word “log” in the file name. To do this, you’d enter find /home/analyst/projects -name "*log*". You could also enter find /home/analyst/projects -iname "*log*".

In these examples, the output would be all files in the pro_______ directory that contain log surrounded by zero or more characters. The "*log*" portion of the command is the search criteria that indicates to search for the string “log”. When -name is the option, files with names that include Log or LOG, for example, wouldn’t be retu_______ because this option is case-sensitive. However, they would be returned when -iname is the option.

Security analysts might also use find to find files or directories last modified within a certain time frame. The -mtime option can be used for this search. For example, entering find /home/analyst/projects -mtime -3 returns all files and directories in the projects directory that have been modified within the past ________ days.

The -mtime option search is based on days, so entering -mtime +1 indicates all files or directories last modified more than one day ago, and entering -mtime -1 indicates all files or directories last modified le_____ than one day ago.

1. Navigate to the /home/analyst/logs directory.

2. Use grep to filter the server_logs.txt file, and return all lines containing the text string error.