Work the Shell - Looking More Closely at Letter and Word Usage

More examples of using the shell to find the frequency of letters used in the English language.

Dave Taylor has been hacking shell scripts for over thirty years. Really. He's the author of the popular "Wicked Cool Shell Scripts" and can be found on Twitter as @DaveTaylor and more generally at


Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

missing the n in the newline substitution

Anonymous's picture

$ cat dracula.txt | tr ' ' '\
' | grep -v '[^[:alpha:]]' | grep -v "^$"

shoule be:

$ cat dracula.txt | tr ' ' '\n
' | grep -v '[^[:alpha:]]' | grep -v "^$"

unless I am missing something ;)

Bash is not C or Python or ...

Mitch Frazier's picture

Ending a line with a backslash is the correct way to escape a newline in bash. In many languages, such as C, the backslash gives the next character special significance (eg \n causes the n to become a newline in the string). In bash, on the other hand, the backslash removes any special significance that the next character has. So a backslash as the last character on the line causes the next character (a real newline) to lose its special significance (which is to end a command line) and become a regular character.

The newline case is a bit strange for sure and causes some funny looking code sometimes, I tend to do this instead:



cat dracula.txt | tr ' ' "$newline" | grep ...

That makes it a bit more explicit as to what's happening and you only have to see the "weirdness" once at the top of your script.

Also note, that in Dave's example the newline is not actually required since it appears inside a quoted string. Bash won't recognize a newline as the end of a command if there is an open quoted string, so it just puts the newline into the string. So, the following will work also:

$ cat dracula.txt | tr ' ' '
' | grep -v '[^[:alpha:]]' | grep -v "^$"

Mitch Frazier is an Associate Editor for Linux Journal.

White Paper
Linux Management with Red Hat Satellite: Measuring Business Impact and ROI

Linux has become a key foundation for supporting today's rapidly growing IT environments. Linux is being used to deploy business applications and databases, trading on its reputation as a low-cost operating environment. For many IT organizations, Linux is a mainstay for deploying Web servers and has evolved from handling basic file, print, and utility workloads to running mission-critical applications and databases, physically, virtually, and in the cloud. As Linux grows in importance in terms of value to the business, managing Linux environments to high standards of service quality — availability, security, and performance — becomes an essential requirement for business success.

Learn More

Sponsored by Red Hat

White Paper
Private PaaS for the Agile Enterprise

If you already use virtualized infrastructure, you are well on your way to leveraging the power of the cloud. Virtualization offers the promise of limitless resources, but how do you manage that scalability when your DevOps team doesn’t scale? In today’s hypercompetitive markets, fast results can make a difference between leading the pack vs. obsolescence. Organizations need more benefits from cloud computing than just raw resources. They need agility, flexibility, convenience, ROI, and control.

Stackato private Platform-as-a-Service technology from ActiveState extends your private cloud infrastructure by creating a private PaaS to provide on-demand availability, flexibility, control, and ultimately, faster time-to-market for your enterprise.

Learn More

Sponsored by ActiveState