You can view the declarations along with other environment variables using the declare command. You can explicit define an array: declare -a MY_ARRAY Here is exactly how the my_array is stored on BASH: my_array=(="zero" ="one" ="two" ="three" ="four") If you want to make the width variable, you can pass an asterisk instead of a number, and printf will use the next number it finds in the argument list.Arrays are collection of elements, The Arrays in bash are indexed from 0 (zero-based).īelow is the definition on an Array in Bash If you pass a negative number as the width, the directive will be left-justified instead of right-justified. Since 25 has only two digits, spaces are added to the remaining characters. The %5d format specifier in the output denotes that the formatted string will contain a minimum of five characters. Unused characters will be filled in with spaces.įor example, typing printf "%s:%5d\n" "Value 1" 25 "Value 2" 120 will output: Value 1: 25 You can format your strings with spacing by defining, before the directive specifier, a minimal number of characters printed. To print Unicode characters with printf, use the \u escape for 16-bit Unicode and \U for 32-bit Unicode.įor example, you can print the copyright symbol with the following command: $ printf "\u00A9" You can see the format specifiers for month, day, year, hour, minute, and second in the aforementioned output. To print the current date and time, you can combine printf with the date command and pass the following directives. If you need to format a hexadecimal number, use %x for lowercase and %X for uppercase. Just place your expression inside of double parentheses like you normally do in Bash, and specify the expression in the arguments list. Output Math Functions Using printfįormatting math functions with the printf command is easy. Related: What Does "Bash" Mean in Linux? 3. Note that if you want to use an unsigned decimal in the output, you will have to use the %u directive instead. To format a string with an integer, you can use the %d directive for a signed decimal. MUO is one of the largest online technology publications. $ printf "%s is one of the largest online %s." MUO "technology publications" To format the output with strings of text, use the %s directive. But today we'll only be covering some common ones for the function. Printf features many format specifiers that you can use in your scripts.
Now that you know how Bash scripting with printf in Linux works, you're ready to start using it in your commands. You should also be aware that if an argument is missing, printf will interpret any directives as 0 (for a number) and null (for a string).
You can use this to your advantage, but if you're not careful, you can end up with results like this: $ printf "My name is %s " Jordan Gloor It's important to keep in mind that printf will attempt to reuse the format for all of your arguments. To print a string and then move to a new line, type printf "Hello, world\n". Thus, you'll need to use the new line character \n in each instance. Unlike the echo command, printf won't assume you want a new line after the output is printed. You may notice that after the output, Bash doesn't create a new line for you. Printf took the world argument and replaced the %s character in the specified string with it. Note the output of the following command: $ printf "Hello, %s" world Printf will print the format string while implementing escapes ( \) and directives ( %) through the use of specified arguments. The basic syntax for printf is: printf format
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