Without much introduction or discussion, here’s a Scala example that shows how to read from one text file while simultaneously writing the uppercase version of the text to a second output file:
If you ever need to copy text (or a text file) from the MacOS Terminal to the Mac clipboard, I can confirm that the macOS
pbcopy command works. It reads from STDIN and copies the text to the clipboard, so commands like these work:
$ echo "foo bar baz" | pbcopy $ cat /etc/passwd | pbcopy
Printing columns of information from Unix text files is easy, especially using commands like awk, perl, and more recently, ruby. This short tutorial shows my old-school
awk way of doing this.
awk column printing examples
Suppose you have a file named foo with contents like this:
1 2 3 a b c
You can easily use
awk to print columns of information from this file. Here are a few examples that show how to print the data columns from the file:
This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 12.5, “How to process a CSV file in Scala.”
You want to process the lines in a CSV file, either handling one line at a time or storing them in a two-dimensional array.
Combine Recipe 12.1, “How to Open and Read a Text File” with Recipe 1.3, “Splitting Strings”. Given a simple CSV file like this named finance.csv:
This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 12.4, “How to process every character in a text file in Scala.”
You want to open a text file and process every character in the file.
If performance isn’t a concern, write your code in a straightforward, obvious way:
I've been having some problems with a GoDaddy website lately (see my GoDaddy 4GH performance problems page, and in an effort to see if the errors were related to a MySQL database problem, I created the Drupal/PHP script shown below.
Unix/Linux shell script FAQ: How do I write a Unix or Linux shell script where I "do something" for every line in a text file?
Solution: An easy way to process every line in a text file is to use a Unix/Linux while loop in combination with the Linux cat command, like this:
I had a problem with this website last Wednesday, and as part of troubleshooting the problem, I need to look at one of the Drupal database tables, specifically the
watchdog table. This table had thousands of records in it, and I couldn't find what I needed with SQL
SELECT queries, so I finally dug through the MySQL documentation, and found that I could save the output from a
SELECT query to a text file.
In this tutorial I'll show you both (a) how to save the results of a MySQL query to a text file, and also (b) how to log your entire MySQL session to a text file.
Perl CSV column data extraction FAQ: Can you share an example of how to extract one or more columns from a Perl CSV file or other similarly-formatted flat text file?
Perl is a terrific language for text processing, but several readers have written wondering about how to extract columns of data from text files with Perl. For instance, when you have a text database that looks like this:
Problem: You have a file that should be a plain text file, but for some reason it has a bunch of non-printable binary characters (also known as garbage characters) in it, and you'd like a Ruby script that can create a clean version of the file.
Solution: I've demonstrated how to do this in another blog post by using the Unix tr command, but in case you'd like a Ruby script to clean up a file like this, I thought I'd write up a quick program and share it here.