Mac command to view last login/wake/sleep/charge times

The pmset utility on mac is quite useful for viewing system logs. If you type:

you’ll be able to see some cool system logs. However, as a timesaver, here’s a no-bullshit command to view the following times:

  • When mac went into sleep
  • When mac came out of sleep
  • Charge levels
  • Standby times


Bulk edit filenames using shell

Unix/linux command to remove specific matching text from all files. In this case, I had a list of tiles that had suffix. I wanted to rename them all so that they had just .properties suffix instead. For example, if a file was named, I wanted it to be renamed to

As usual, rather than wasting my time and doing it manually 100 times, I set myself to find an automated way of doing it. And sure enough, I found it!

Here it is:

The above command finds all files that end with For each file that match that criteria, we then rename it to a name that has -defaults stripped out. To strip out the name, we use sed command and to rename we use mv command.

Tested on mac running oh-my-zsh.

Useful unix file editing commands

Find and replace text matching a regular expression in a single file

The above command searches for the (something\-[\da-zA-Z]+) regular expression and replaces it whole (because of the parenthesis which means to select the text matching the expression within) with ToReplace. The g in the end indicates that the operation will be applied to all matches in the file as supplied in path/to/file.txt argument. The -i parameter along with '' suggests the sed command to perform the edit on the file itself, without creating a new copy.

Find and replace text matching a regular expression in files matching name

The above command finds file within /base/directory whose names match *.txt format. Later we combine the output of this with xargs which appends each line of output (path to each matching file) to the following sed command. The -n 1 argument to the xargs command tells it to supply each line of argument one by one to the sed command.

Find and replace text matching a regular expression in files whose contents match a regular expression

In the above command we use the basic find command to get a list of files that we want to do the search in. Then we use grep to recursively find in those files. Now in the above command we don’t really need the -r flag for grep because the find command will list full paths to those files, but we would need it if we were doing find on a relative path instead (like .). The -l flag for grep here will only list the paths to the files that it found having the content TextToFindInFiles and not the actual matching contents like it usually prints. This list of the files is then outputted to the xargs command which then subsequently runs the sed command.


Documenting project information with Maven

In most projects I’ve worked on, the project information is captured in some sort of file. While this has its strengths, such as ability to write free form text and embed images, it doesn’t quite fit with the project because when the artifact is produced during the build time, the read me is not checked into the artifact repository along with it. So how do I know who the contributors were for that specific artifact version? How do I know where the project was hosted at the time?

Well, today I learned that maven provides ability to capture some of those attributes and some more! I like this because it means that when the artifact gets checked in (along with its pom.xml) the details about the project are captured for that version, frozen in time.

Great thing about these attibutes is that when you run mvn site they are used in the project information html page that maven produces. Technically, then you can upload this to any statically hosted site location, all versioned up and ready to be explored.

Ok so lets begin exploring these attributes. The first three attributes are the basic ones:

For people working in corporations and companies, the following might be useful, especially when open sourcing the project:

Additionally, the licenses tag can be used to describe some licensing information. How many times have you come across a project that has changed the licensing information half way through versions? This is a life saver (at least legally)!

Some source control information is also useful, however, whats more useful is knowing where to go in order to raise issues. In most companies, people use source control to store code but then use an alternative mechanism like Jira or Trello to mange issues. The scm and issueManagement tags are useful here in clarifying such information:

Developer information on projects is very useful. Companies don’t usually like this because, well, developers are supposed to be expendable, however, in my humble opinion, it is useful to list developers who were working on the project at the time. This way the versions can be tracked, at least to the lead working on it at the time. Use it thusly:

For contributors, people who have worked on the project, although not necessarily part of it exclusively, use:

Lastly, it is useful to capture some information about pipeline that was used to create the project. For this, maven has ciManagement tag:

The above is just a small example of what you can do with these attributes, there are many more sub-attributes that you can explore. Hope this is a good introduction and kicks off some ideas of what you can do with this information.

Finding classes in jar/war files

Recently I was out looking for classes that were present in my Web Application Archive (WAR) file. Why? Well, I was out combating Jar Hell. As I am allergic to doing things manually, here’s a small command I constructed to help me find classes within jar files:

The above command prints out class file as well as the name of the jar file that class is present in. If you’re looking just for the path where the classes are present, you can just run: