Command replacement-$ (), reverse quotation marks

Command replacement can use the output of a command as an extension mode.

Introduction

Command replacement can use the output of a command as an extension mode.

Format:

$ (Ls)

As follows:

[Root @ allyes20121031 de_info_center] # echo $ (ls)

2. txt argv. cpp argv. h config. cpp config. h countlogs_data.h de_info_d_socket de_info.h de_information_center de_information_center_config.txt domain_socket_client.h domain_socket.h fork_management.h global. cpp global. h internet_socket.h log. h log_record.h log.txt main. cpp server_data.h shell_script task. h task_id_center.h task_management.cpp task_management.h task_result task_result.h tmp

[Root @ allyes20121031 de_info_center] #

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Reverse quotation marks

In earlier shell programs, there were also reverse quotation marks.

As follows:

[Root @ allyes20121031 de_info_center] # echo 'Ls'

2. txt argv. cpp argv. h config. cpp config. h countlogs_data.h de_info_d_socket de_info.h de_information_center de_information_center_config.txt domain_socket_client.h domain_socket.h fork_management.h global. cpp global. h internet_socket.h log. h log_record.h log.txt main. cpp server_data.h shell_script task. h task_id_center.h task_management.cpp task_management.h task_result task_result.h tmp

[Root @ allyes20121031 de_info_center] #

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