# Create and populate the file with your data
touch who_tb_data.txt
echo "country year type count
Afghanistan 1999 cases 745
Afghanistan 1999 population 19987071
Afghanistan 2000 cases 2666
Afghanistan 2000 population 20595360
Brazil 1999 cases 37737
Brazil 1999 population 172006362
Brazil 2000 cases 80488
Brazil 2000 population 174504898
China 1999 cases 212258
China 1999 population 1272915272
China 2000 cases 213766
China 2000 population 1280428583" > who_tb_data.txt
# Get the word count values
counts=$(wc who_tb_data.txt | awk '{print $1, $2, $3}')
# Use printf to format the output
printf " lines words characters\n"
printf "%8s %7s %10s\n" $countsFormat
To make the commands above more generalizable so that any file can be passed as input rather than being restricted to a specific file (who_tb_data.txt), we can modify the script to take a filename as a command-line argument.
This way, you can use the script with any file by specifying the filename when you run the script.
Step 1: Modify the Script to Take Command-Line Arguments
Here’s how the revised script could look:
#!/bin/bash
# Check if a file name was provided as an argument
if [ "$#" -ne 1 ]; then
echo "Usage: $0 <filename>"
exit 1
fi
# Check if the file exists
if [ ! -f "$1" ]; then
echo "File not found: $1"
exit 1
fi
# Get the word count values
counts=$(wc "$1" | awk '{print $1, $2, $3}')
# Use printf to format the output
printf " lines words characters\n"
printf "%8s %7s %10s\n" $countsStep 2: Save and Make the Script Executable
Save the script in a file, for example,
format_wc_output.sh.Make sure the script is executable:
chmod +x format_wc_output.sh
Step 3: Run the Script with a File as an Argument
Now you can run the script with any file as an argument. For example:
./format_wc_output.sh somefile.txt
Explanation
Argument Checking: The script now starts by checking if exactly one argument (the filename) is provided. If not, it prints a usage message and exits. This ensures the user knows how to run the script correctly.
File Existence Checking: It checks if the file exists before attempting to process it. If the file doesn’t exist, it prints an error message and exits. This prevents errors related to non-existent files.
Using Command-Line Argument: The
wccommand now uses$1, which is a placeholder for the first command-line argument provided to the script (i.e., the filename you want to process).
This version of the script is more flexible and useful, as it can handle any file input, making it a handy tool for quickly formatting word count output for various files across your system.