This lesson's interactive features are locked, please to keep using them
Standard Error
Standard Error, usually called stderr, is a data stream just like standard output, but is intended to be used for error messages.
It's a separate stream so that you can redirect it to a different place if need be, but by default, it prints to your terminal just like stdout.
Redirecting Streams
You can redirect stdout and stderr to different places using the > and 2> operators. > redirects stdout, and 2> redirects stderr.
Redirect stdout to a File
echo "Hello world" > hello.txt
cat hello.txt
# Hello world
Redirect stderr to a File
cat doesnotexist.txt 2> error.txt
cat error.txt
# cat: doesnotexist.txt: No such file or directory
In this example, cat is used to intentionally generate an error message (since the file doesn't exist), which is then redirected to error.txt.
Assignment
There's a worldbanc/private/bin/process_transactions.sh script that:
- Accepts a path to a CSV file containing transactions data as a positional argument (or CLI argument).
- Prints modern transactions (after the year 2000) to
stdout, and old transactions (before 2000) tostderr.
Submit the shell checks.
The temporary directory (/tmp) exists by default on all Unix-like systems, in your root directory. Files there are deleted by your system routinely. It's a great place to store temporary files that you don't need to keep around.
Tip
SCRIPT_PATH PATH_TO_CSV 2> /tmp/worldbanc.log