Method 1: Make the/etc/profile file effective immediately after modification method 1: www.2cto.com make the/etc/profile file effective immediately after modification, you can use the following command :#. /etc/profile Note :. and/etc/profile have space method 2: Make the/etc/profile file take effect immediately after modification, you can use the following command: # source/etc/profile attachment: use the source command in Linux. The source command is also called the "dot command", which is also a dot symbol (.). The source command is usually used to re-execute the modified initialization file to make it take effect immediately without logging out and logging on again. Usage: The source filename or. filename source command has another usage besides the preceding usage. When compiling the system core, you often need to enter a long string of commands, such as: make mrproper make menuconfig make dep make clean make bzImage ............ If you make these commands into a file and execute them in sequence automatically, it is very convenient for users who need to recompile the core of the system multiple times. You can use the source command to achieve this, its role is to take the content of a file as shell to execute, first in the linux source code directory (such as/usr/src/linux-2.4.20) to create a file, such as make_command, enter the following content: www.2cto.com make mrproper & make menuconfig & make dep & make clean & make bzImage & make modules & make modules_install & cp arch/i386/boot/bzImage/boot/ vmlinuz_new & cp System. map/boot & vi/etc/lilo. after the conf & lilo-v file is created When compiling the core, you only need to input: source make_command under/usr/src/linux-2.4.20, if you are not using lilo to guide the system, you can remove the last two lines, configure your own boot program to guide the kernel. By the way, the & command indicates that the commands connected by it are executed sequentially, but the commands following it can be executed only after the previous commands are successfully executed.