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How to use multiple conditions in shell script?
). Use [ [ instead. Note that I’ve reduced this to two separate tests joined by ||, with the && moved inside the tests. This is because the shell operators && and || have equal precedence and are simply evaluated from left to right.
When do you need to repeat multiple lines in Bash?
When the action block to be repeated is multiple lines, the repetition is too painful and one of the earlier versions is preferable — or you need to wrap the actions into a function that is invoked in the different thenblocks. Share Improve this answer Follow edited May 3 ’15 at 15:43 answered Sep 29 ’10 at 22:51
Why do you not use parentheses in Bash?
Strictly, the parentheses aren’t needed because the precedence of -aand -omakes it correct even without them.
Which is the equivalent shell operator A & B or C & D?
This is because the shell operators && and || have equal precedence and are simply evaluated from left to right. As a result, it’s not generally true that a && b || c && d is equivalent to the intended ( a && b ) || ( c && d ).
How to make conditional statements in shell script?
Conditional Statements | Shell Script. 1 if statement. 2 if-else statement. 3 if..elif..else..fi statement (Else If ladder) 4 if..then..else..if..then..fi..fi.. (Nested if) 5 switch statement.
How to use two variables in the same loop in Bash?
If you don’t mind going off the beaten path (bash), the Tool Command Language (TCL) has such a loop construct: Basically, the loop reads: for each item1 taken from list1, and item2 taken from list2. You can then replace command_name with your own command. Is this answer outdated? This might be another way to use two variables in the same loop.
How to use multiple conditions in while loop?
# Single POSIX test command with -o operator (not recommended anymore). # Quotes strongly recommended to guard against empty or undefined variables. while [ “$stats” -gt 300 -o “$stats” -eq 0 ] # Two POSIX test commands joined in a list with ||.