Set-x and set + x commands

Set-x and set + x commands are used for script debugging. Set is to print the commands below it to the screen. set-x is to enable set + x, set-o is to view (xtrace), and set is to catch up with the display of a piece of code. It is valid for the entire script after the set-x is executed. [Root @ mybox bin] # ls-l/bin/bash + ls -- color = tty-l/bin/bash-rwxr-xr-x 1 root 722684 Jul 12 2006/ bin/bash for some scripts, set-x and set + x can be used together. For example, in a script: set-x # activate debugging from herewset + x # stop debugging from here, the execution method of the shell can be set, you can set the variable according to different requirements.-a indicates the modified variable for output to the environment variable. -B: immediately returns the execution STATUS OF THE terminated background program. -C: The generated file cannot overwrite the existing file. -D Shell uses the command used by the table to accelerate the execution of the command. The-d parameter can be canceled. -E. If the return value of the command is not equal to 0, exit the shell immediately. -F cancels the use of wildcards. -H automatically records the location of the function. -H Shell can use "! "Add <command number> to execute commands recorded in history. The parameters given by the-k Command are considered as the environment variables of the command. -L record the variable name of the for loop. -M uses the monitoring mode. -N: only read commands, not actually executed. -P starts the priority mode. After the-P parameter is started, the symbolic connection is replaced by the actual file or directory when the command is executed. -T run the subsequent command to exit the shell. -U: an error message is displayed when undefined variables are used during execution. -V displays the input values read by shell. -X: After the command is executed, the command and its parameters are displayed first. + <Parameter> cancel a parameter that was started by a set.