Linux built-in commands and external commands

1, the Linux command can be divided into internal commands and external commands:

The built-in commands are memory-resident when the system is started, so the execution efficiency is high.

The external command is the software function of the system, and the user is required to read the memory from the hard disk.

2. Type-display Information about command type

#查看当前系统的命令是否为内置命令和外部命令.

3, Bash_builtins
Alias, BG, bind, break, BUILTIN, caller, CD, command, Compgen, complete, compopt, continue, declare, dirs, disown, EC Ho,enable, eval, exec, exit, export, False, FC, FG, Getopts, hash, help,history, jobs, kill, let, local, logout, mapfile , popd, printf, pushd,pwd, read, ReadOnly, return, set, shift, shopt, source, suspend, Test,times, trap, True, type, Typ ESET, Ulimit, Umask, Unalias, unset, wait

#Linux中所有的内置命令.

4. Summary of built-in commands and external commands

In RHEL6 we say that which can only search the path variable for the absolute path of the command, built-in commands are built into bash, so we can't find the absolute path to the command,

But, in the RHEL7, it seems to optimize the feature, built-in commands in the PAHT environment can find the absolute path of the command

Linux built-in commands and external commands