$ unset x $ showvar $x is not set $ x=3 $ showvar $x is not set $ export x $ showvar $x = 3 $ x= ## in bash, reassignment doesn't remove a variable from the environment $ showvar $x is set but empty 注意 showvar不是一个 bash 命令,而是一个如清单 5-1 所示的脚本,...
`whoami`command shows the username of the currently logged in user. By default, this command is stored in/usr/bin/folder. Run the following script to run `whoami`command using path and store in the variable,$output,and print the value of$output. $output=$(/usr/bin/whoami) $echo$output...
In this script,%oinprintf “%o”specifies the format to treat the input variabledecimalNumberas an octal number, effectively converting it from decimal to octal. It’s time to execute the script: # bashdecimal_to_octal.sh This command runs the script, prompting you to enter a decimal number...
The variable name is on the left hand side of the equals sign, and the data which will be stored in that variable is on the right hand side of the equals sign. Notice that there are no spaces on either side of the equals sign, this is not allowed when assigning variables: chapter_nu...
# Print the value of the variable name stored in 'hello_$var'. $ printf '%s\n' "${!ref}" value 1. 2. 3. 4. 5. 6. 7. 8. 9. 或者,在bash4.3+上: $ hello_world="value" $ var="world" # Declare a nameref. $ declare -n ref=hello_$var ...
The proper way to handle errors is to check if the program finished successfully or not, using return codes. It sounds obvious but return codes, an integer number stored in bash$?or$!variable, have sometimes a broader meaning. Thebash man pagetells you: ...
#use that variable echo “Hello $NAME” The user can also fill in variables through user input: #!/bin/bash echo “Hello $1, that is a $2 name” In the terminal: ~$bash name.sh “William” “great” Hello William, that is a great name ...
we’ve created an array namedfruitswith three elements: ‘apple’, ‘banana’, and ‘cherry’. The ‘for’ loop then iterates over each element in the array. For each iteration, the current element’s value is stored in thefruitvariable, which we then use in theechocommand to print out...
value of theTEXTDOMAINshell variable, possibly adding a suffix of ‘.mo’. If you use theTEXTDOMAINvariable, you may need to set theTEXTDOMAINDIRvariable to the location of the message catalog files. Still others use both variables in this fashion:TEXTDOMAINDIR/LC_MESSAGES/LC_MESSAGES/TEXTDOMAIN...
sets the number of commands that are saved in your history list. By default, this value is 500. These previously issued commands (known as your history list) are stored in your history file. Its default location is~/.bash_history, and this location is stored in the shell variableHISTFILE....