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When to run command2 only if command1 succeeded?
Using a single ampersand (&) will cause the first command and then the second command to be run in sequence. Using double ampersands (&&) introduces error checking. The second command will run only if the first command is successful. command2 is executed if, and only if, command1 returns an exit status of zero.
How to abort the last command run in Bash?
If you want to know the previous command’s return status as well, save both in a single command. Furthermore, if you only want to abort on a failed commands, use set -e to make your script exit on the first failed command.
Is there racecondition between last error and last command?
There is a racecondition between the last command ($_) and last error ( $?) variables. If you try to store one of them in an own variable, both encountered new values already because of the set command. Actually, last command hasn’t got any value at all in this case.
When do you enter a command in the history?
Only complete commands are entered in the history. For example, the case construct is entered as a whole, when the shell has finished parsing it. Neither looking up the history with the history built-in (nor printing it through shell expansion ( !:p )) does what you seem to want, which is to print invocations of simple commands.
How to run two or more commands at once in Linux?
Here’s a useful summary of each of the operators used to combine commands: 1 A ; B – Run A and then B, regardless of the success or failure of A 2 A && B – Run B only if A succeeded 3 A || B – Run B only if A failed
How to run multiple commands in cmd.exe?
When using cmd.exe, you can put multiple commands on the same line by using ‘&’ or ‘&&’ between commands. Using a single ampersand (&) will cause the first command and then the second command to be run in sequence. Using double ampersands (&&) introduces error checking. The second command will run only if the first command is successful.
What does it mean to combine two commands on a command line?
Combining two or more commands on the command line is also known as “command chaining”. We’ll show you different ways you can combine commands on the command line. The semicolon (;) operator allows you to execute multiple commands in succession, regardless of whether each previous command succeeds.