tailieunhanh - Linux all in one desk reference for dummies phần 3

Tham khảo tài liệu 'linux all in one desk reference for dummies phần 3', công nghệ thông tin, hệ điều hành phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 160 Discovering and Using Linux Commands The Linux wc command comes to the rescue. The wc command displays the total number of characters words and lines in a text file. For example type wc etc inittab and you see an output similar to the following 75 304 2341 etc inittab In this case wc reports that 75 lines 304 words and 2341 characters are in the etc inittab file. If you simply want to see the number of lines in a file use the -1 option and type wc -l etc inittab. The resulting output should be similar to the following 75 etc inittab As you can see with the -1 option wc simply displays the line count. If you don t specify a filename the wc command expects input from the standard input. You can use the pipe feature of the shell to feed the output of another command to wc which can be handy sometimes. Suppose you want a rough count of the processes running on your system. You can get a list of all processes with the ps ax command but instead of counting lines manually just pipe the output of ps to wc and you get a rough count automatically ps ax wc -l 76 Here the ps command produced 76 lines of output. Because the first line simply shows the headings for the tabular columns you can estimate that about 75 processes are running on your system. Of course this count probably includes the processes used to run the ps and wc commands as well but who s really counting Sorting text files You can sort the lines in a text file by using the sort command. To see how the sort command works first type more etc passwd to see the current contents of the etc passwd file. Now type sort etc passwd to see the lines sorted alphabetically. If you want to sort a file and save the sorted version in another file you have to use the Bash shell s output redirection feature like this sort etc passwd This command sorts the lines in the etc passwd file and saves the output in a file named in your home directory. TEAM LinG - Live Informative Non-cost and Genuine .