Creating a Directory in AIX KornShell (ksh) Only If It Isn't Already There

Creating a Directory in AIX KornShell (ksh) Only If It Isn't Already There
Creating a Directory in AIX KornShell (ksh) Only If It Isn't Already There
Louis Robert
Monday, July 8, 2024 at 10:50:22 AM

Managing Directory Creation in KornShell Scripts

When developing shell scripts in KornShell (ksh) on AIX, there are times when you need to create a directory if it does not already exist. Using the mkdir command is simple, however complexities emerge if the directory already exists, resulting in an error message.

To avoid the "File exists" problem, add a check or disable the error message in your script. This article discusses efficient strategies for ensuring that your directory creation commands operate smoothly and without mistakes.

Command Description
-d Used with the test command to determine whether or not a directory exists.
mkdir -p Creates a directory and its parent directories, concealing errors if the directory already exists.
2>/dev/null Redirects standard error to null, thereby essentially concealing error messages.
$? Represents the last command's exit status.
echo Prints a message to standard output.
if [ ! -d "directory" ] Conditional statement that checks if the supplied directory does not exist.

Understanding KornShell Directory Management

Before creating a directory, the first script checks to see if it already exists. The if [ ! -d "directory" ] conditional statement checks if the provided directory is not present. If the directory does not exist, the script will create it using the mkdir "directory" command. This technique prevents the "File exists" problem by ensuring the directory is only created if it does not already exist. Furthermore, a echo command offers feedback, alerting the user whether the directory was created or already existed.

The second script uses the mkdir -p command with error suppression. The -p parameter ensures that no error is generated if the directory already exists, while also creating any necessary parent directories. By redirecting errors to /dev/null with 2>/dev/null, the script avoids any error messages that may occur if the directory already exists. This script verifies the exit status of the mkdir command using $? and provides suitable feedback. If the exit status is zero, it means the directory was created or already existed; otherwise, it signals a failure.

KornShell creates a directory conditionally.

Shell script with KornShell (ksh) on AIX.

#!/bin/ksh
# Check if the directory does not exist, then create it
DIRECTORY="/path/to/directory"
if [ ! -d "$DIRECTORY" ]; then
  mkdir "$DIRECTORY"
  echo "Directory created: $DIRECTORY"
else
  echo "Directory already exists: $DIRECTORY"
fi

Suppressing Error Messages While Creating a Directory

Using mkdir with error suppression in KornShell.

#!/bin/ksh
# Attempt to create the directory and suppress error messages
DIRECTORY="/path/to/directory"
mkdir -p "$DIRECTORY" 2>/dev/null
if [ $? -eq 0 ]; then
  echo "Directory created or already exists: $DIRECTORY"
else
  echo "Failed to create directory: $DIRECTORY"
fi

Advanced Methods for Directory Creation in KornShell

Beyond basic directory creation and error suppression, advanced KornShell (ksh) programming can provide more powerful solutions for directory management. One such option is to incorporate logging and notifications inside the script. This is especially useful in production contexts, where keeping track of directory creation attempts is critical. Appending log entries to a file allows you to keep track of all directory operations, which is useful for debugging and auditing. This can be accomplished by using echo statements to write to a log file.

Another advanced method is to integrate the script with other system monitoring tools. For example, you could use KornShell and cron tasks to schedule regular checks and ensure that relevant folders are always available. If a directory is lacking, the script can create it and send an email to administrators. This proactive strategy helps to keep the system running smoothly and guarantees that essential directories are always available for critical applications.

Frequently Asked Questions: Directory Management in KornShell

  1. How do I check if a directory exists in KornShell?
  2. Use the if [ -d "directory" ] command to see if a directory exists.
  3. How does the -p flag affect the mkdir command?
  4. The -p flag creates the directory and any necessary parent directories, and does not generate an error if the directory already exists.
  5. How can I turn off error warnings from the mkdir command?
  6. Redirect the error output to /dev/null via 2>/dev/null.
  7. What's the point of testing $? after a command?
  8. It verifies the previous run command's exit status, with 0 representing success.
  9. How do I track directory construction attempts?
  10. Use echo statements to append messages to a log file, creating a history of operations.
  11. Can I use KornShell to schedule regular directory checks?
  12. Yes, utilize cron jobs to schedule scripts that check and create directories when necessary.
  13. How do I send notifications when a directory is created?
  14. Integrate the script with the mail command to send email notifications when the directory is created.
  15. Is it possible to create many directories simultaneously?
  16. Yes, use mkdir -p "dir1/dir2/dir3" to create nested directories in a single command.

Final Thoughts About Directory Creation

To effectively manage directory creation in KornShell scripts, check for existing directories or suppress errors that already exist. Using conditional statements or the mkdir -p command helps simplify your scripts and eliminate redundant error messages. Advanced approaches like logging, notifications, and automation with cron jobs improve the robustness and dependability of your directory management procedures, ensuring that your scripts execute smoothly and quickly.