a – shell functions return codesfunction return codes are used to indicate the success or failure of a function’s execution.also known as exit statusesa return code of 0 indicates successful executionwhile any other value indicates an error or failure.return 0 → returns 0 for successful executionreturn 1 → return 1 for non succesful executioncheck_success $?…
a – flow control in shell scriptsflow control is an essential aspect that allows you to manage the execution of commands…based on certain conditions or loops.It helps in structuring the script to perform different tasks under varying circumstances.Shell scripting supports several flow control constructs, such as if, for, while, and until loops.Key Flow Control Constructs…
a – test command part 1test command is used to evaluate conditional expressionsit returns an exit status based on whether the expression evaluates to true or false.It can be used in if statements, loops, and case statements.test command has a wide range of expressions:file, string and integer expressionsCommon uses:Numeric comparisons: -eq, -ne, -lt, -le, -gt,…
a – extended test command in shell scriptsUnlike the traditional [ ] (or test) which requires spaces around operators, [[ ]] does not have this requirement.It’s generally recommended to use [[ ]] over [ ] for most modern shell scripting needs due to its enhanced functionality and error prevention.Unlike [ ], [[ ]] does not…
a – while loop in shell scriptswhile loop executes its block of commands as long as the given condition remains truesyntaxwhile [ condition ]; do Commands to executedone[ condition ] is evaluated before each iteration. If the condition evaluates to true, the commands inside the loop are executed.Once the commands finish executing, the condition is…
a – case command introductionThe case statement is used for conditional execution based on the value of a variable or expression.It provides a more readable and compact alternative to multiple if-elif-else statements…when you have a limited set of possible values to check against.syntaxcase variable in pattern1) commands if variable matches pattern1 ;; pattern2) commands if…
a – for loop in shell scripts introfor loop is used to iterate over a sequence of items or valuesThis type of loop is very useful for executing the same command or set of commands multiple times with different inputs.syntax: for variable in item1 item2 … itemNdo Commands to be executed for each iterationdonevarialbe is…
a – what is parameter expasion in shell scripts part 1Parameter expansion in a shell script allows you to manipulate variable values in various ways…such as substring extraction, default value assignment, and pattern replacement.common parameter expansions:1. Substring Extraction: ${variable:position} → Extracts the substring from the specified position to the end.${variable:position:length} → Extracts a substring of…
a – Case conversion with parameter expansioncase conversion is converting strings to uppercase or lowercaseIt can be performed using several methods, depending on the shell and the context of the script1. with Parameter Expansion ^^ and ,,Pros:Clean and readable.Fast and efficient.No external commands needed.Cons:Not portable to non-Bash shells (like dash, ksh, or zsh without set…
a – Numbar bases in shell scriptsyou can use variables with different bases by prefixing them with 0x for hexadecimal, 0 for octal, and 0b for binary.*num_hex=0x1A → hexadecimalnum_oct=025 → octalnum_bin=0b1010 → binarywhen dealing with numbers in shell scripts, the shell might not handle leading zeros in variables.025 it might be treated as decimal 25so…
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