The Bash if statement is a fundamental construct that allows you to control the flow of your scripts based on specific conditions. By leveraging conditionals, such as numeric and string comparisons, and file and directory checks, you can create dynamic and responsive scripts. Additionally, nesting ...
I'm not sure what your && find statement is doing...try like this:#!/bin/bash read -p "enter file name: " source file=$source if [[ -f "$file" ]]; then echo "the file exists." else echo "the file does not exist." fi ...
echo "The file does not exist." fi In above example, we are checking whether a file “migratedb.sh” exists or not. If-elif-else Statement In bash script, if you wish to apply multiple conditions using if statement then use ‘ if elif else’. In this type of conditional statement, i...
The statements[ -z "$X" ]andecho "The environment variable X is not set."andusageare used to test if the string is null (-z) and if so, then perform the echo statement saying that it is not set and invoke the "usage" function discussed below. If your script does not use flags,...
For example, we want to create a directory Pictures, in case it does not exist, instead of writing the check within an else block, we could just negate our test to see if the file exists, in the following manner:#!/bin/bash DIR="/home/user/scripts" if [ ! -d "$DIR" ]; then...
If the condition is false (i.e., "test.txt" does not exist or is not a regular file), the script prints "File does not exist". The "fi" statement marks the end of the "if" block. 3. Write a Bash script that prompts the user to enter their age, and then checks if the age...
Why you should not use the || and && operators instead of a Bash If Statement? Detailed Examples & FAQ How to check if a variable exists or is “null”? How to check if a file exists? How to check if a directory exists? How to check if a command succeeds or failed? How to do...
For example, let’s say that you want to check if the file “/etc/passwd” exists on your filesystem or not. In a script, you would write the following if statement. #!/bin/bash if [[ -f "/etc/passwd" ]] then echo "This file exists on your filesystem." ...
echo "This is not a directory" fi if [ -s $file ] then echo "File size is zero" else echo "File size is not zero" fi if [ -e $file ] then echo "File exists" else echo "File does not exist" fi 运行结果: File has read access ...
因为HDFS设计的是“一次写入，多次读取”，不可以修改数据，只能追加或者删除，所以，如果目标文件或目录在...