Thay thế các tập tin có tên trong một kho lưu trữ băng Danh sách các tập tin trong một kho lưu trữ băng thông tin cập nhật các tập tin có tên trong một kho lưu trữ băng Chất chiết xuất từ tất cả các tập tin có tên từ một kho lưu trữ băng | System Backups and Restores 193 I Table The tar Functions Function Description c Creates overwrites a tape archive r Replaces the named files in a tape archive t Lists the files in a tape archive u Updates the named files in a tape archive x Extracts all the named files from a tape archive Along with these functions the f tar_file command-line argument is used to specify a backup device. If this command-line argument is not used either the backup device specified by the TAPE environmental variable or the backup device identified in the etc default tar file is used. The files or directories to be backed up are listed as command-line arguments after the function and argument. The v option can be used to display the names of files as they are added to or extracted from the archive. In some situations using the tar command to create a single archive of directories and files will result in an archive that uses less space than all the original files and directories. Thus the tar command can be used to reduce storage space requirements. Backing Up a Directory Using the tar Command The following listing shows how the tar command is used to back up the export home directory to the dev rmt 0 tape drive tar cf dev rmt 0 export home Restoring a Directory Using the tar Command The following listing shows the tar command being used to restore the export home directory from the dev rmt 0 tape drive tar xf dev rmt 0 The cpio Command The cpio 1 command can also be used to create an archive of directories and files. The cpio command operates in three modes Copy out -o command-line argument Reads a list of directory and filenames and then copies their contents along with control information to an archive format. 194 Chapter 8 Copy in -i command-line argument Reads an archive to extract the directories and files and recreates them at a specified location on the system. Pass -p command-line argument Reads a list of directories files along with their contents and reproduces them at
