October 23, 2015

10 Mac OS X Terminal Commands for Testers

I really like terminals, command lines, bash scripting etc. They are handy and easy way to automate some routine tasks in my everyday work. Thats why after I saw article Eight Terminal Utilities Every OS X Command Line User Should Know I decided to write something like this, but for testers.

These are OS X commands, but some of them are also working on Linux systems and Windows (if use some UNIX-like terminal like Babun, CygWin or Cmder).

This is defently not the complete list. Here you can find the complete list of all OS X commands, but this post is about my favourite and frequently used (almost) commands.

1. alias
It's the most useful command of all – it allows to replace some command with a short word. That means, that if you have some long command that you regularly run in the terminal you can assign alias to it and use some simple short substitution. For example, you always monitor application logs using tail -1000f application.log, but instead of writing this whole string every day you can create alias like logs and write only 4 letters into the command line. Moreover, you can use autocomplete with aliases (TAB key), just like with regular commands. You can see my previous post Bash Scripts for Working With Documentation for more examples about using alias.

There is one trap that many beginners fall into – you can just type following command into your command line:
alias logs='tail -1000f application.log'
but in that case you create alias only for your current session. That means it'll disappear after you close it. To create permanent aliases you need to put them into specific file, which is usually ~/.bash_aliases. You may also need to add following code into your ~/.bash_profile file (you can add it just to the end):
# Aliases
if [ -f ~/.bash_aliases ]; then
. ~/.bash_aliases
And you need to restart your session for taking these changes into use (just close-open you terminal or exit-login to server).

2. crontab
This one allows you to automate some commands. For example, you have some documentation on SVN (or some similar version control system) and you need to update it regulary to get the latest state. You can add following job into your cron schedule, which updates SVN directory every 10 minutes:
*/10 * * * * svn update ~/Documents/SVN-documentaion
To open crontab editor, where you can insert previous command, you need to run:
crontab -e
(or sudo crontab -e if you are not under admin user)
See Ubuntu CronHowTo article for understanding what are these asterisks mean.

3. grep
Grep is a very powerful tool for finding strings in any output (log files, query responses, script output etc), that you can perform. I use it to filter log files. For example, I can get all rows, where ERROR word is present:
tail -1000 application.log | grep ERROR
Or I can get all rows, where todays date is mentioned in the beginning of the row:
tail -1000 application.log | grep ^23.10.2015
Grep works with regular expressions, so you may need to understand them to perform some complex filtering, but simple search by one word may be enough for you.

4. find
Find searches files in directory. Again, in my previous post Bash Scripts for Working With Documentation I wrote about scripts for finding documents by name or by content – the whole funtionality is done by find there. So I use it in by daily work for finding documents with required data. You can find (ha-ha) a lot of examples in the following article: Find Command in Unix and Linux Examples.

5. open
Simply opens a file, a folder, an application or URL, just as if you had double-clicked the file's icon. It's useful if you first have done some complicated search of required file (using find), got the path of it and open it (with default or some other application).
Second useful case – opening directories (especially hidden ones). For example, open . opens current directory.

6. awk
AWK is actually programming language designed for text processing. It can be used as reporting tool and I usually use it to beautify my scripts' output – for example, to color some words. I am not sure that it's useful for everyday life, but if you want to write your own script, it better has meaningful output.

7. scp
It stands for Secure Copy. It is useful for somebody who works with servers (application updating, logs monitoring etc). With this command you can copy files from one server to other, or from server to your computer and vice versa. You can find some examples in Example syntax for Secure Copy (scp), I copy here one of them:
scp /some/local/directory

8. pbcopy / pbpaste
These two commands may save you from endless scrolling: pbcopy copies output to the clipboard, pbpaste inserts content from the clipboard. For example, you have some log file, that you want to investigate on your computer in you favorite editor. The simplest way is to copy its content to clipboard and paste it into another document. With these commands you don't need to scroll anything to select the text, or google "how to select the whole text in vi" or anything like this, just type:
cat application.log | pbcopy

9. screencapture
Honestly, I don't use this command in my daily work, but I have a feeling that it's important. It does what it says – captures the screenshot. You can set time delay to it and you can write a script for time lapse (taking screenshot every 10 seconds or something like this). It just happens, that I use screenshots quite rarely in my work, but I guess it can be interesting command for testers, who use them a lot.
You can see examples here: Take a screen capture from the command line.

10. sips
Last (and least) one is SIPS – Scriptable Image Processing System. You can use it for processing files, for example, resize all PNG files in current directory to 1024×768 (ignoring aspect ratio):
sips -z 768 1024 *.png
Again, I don't work with screenshots and picture files a lot, but it's the simplest and the fastest way (and cheapest one, comparing to some Photoshop) to process a large amount of picture files (or if you want to work with pictures in your bash script).

Don't forget the alias! You don't need to know all these commands by heart – you can just figure out how you can use them and which parameters suits for your case, put it into the alias thereafter use only short and nice commands.

This one is just for fun (once you've already opened the terminal). Some guys did pretty awsome ASCII version of Star Wars IV. You can run it over the Telnet. I don't know how long does it last – I've watched 15 minutes and Luke only meets Chubaka and Han Solo, so I guess they did the whole movie.

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