Unix Shell Programming Third Edition phần 10 pptx

... Bash shell beginning of line, matching 2nd bg command 2nd 3rd 4th 5th 6th books AWK Programming Language, The Learning Pearl Programming Pearl Unix C Shell Field Guide, The Unix in ... Shell Field Guide, The Unix in a Nutshell[colon] System V Edition Unix Programmer's Manual, Volume II Unix Programming Environment, The Bourne shell Bourne, S...

Ngày tải lên: 13/08/2014, 15:21

... sticky area that is a frequent source of shell programming errors. It's good to really understand the principles here to save yourself a lot of programming headaches in the future. There ... "$count" -ge 0 -a "$count" -lt 10 ] will be true if the variable count contains an integer value greater than or equal to zero but less than 10. The -a operator has lower...

Ngày tải lên: 13/08/2014, 15:21

... special notation is recognized by the shell when writing for commands. If you write for var do command command done (note the absence of the in), the shell automatically sequences through ... yes/no response is executed. The read command that follows causes the shell to wait for you to type something in. Note that the shell does not prompt you when it's waiting for you to ent...

Ngày tải lên: 13/08/2014, 15:21

... shell, such as bash. Three are covered in the third edition of Unix Shell Programming. It begins with a generalized tutorial of Unix and tools and then moves into detailed coverage of shell programming. Topics ... shell, such as bash. Three are covered in the third edition of Unix Shell Programming. It begins with a generalized tutorial of Unix and tools and then m...

Ngày tải lên: 13/08/2014, 15:21

... occurrences of " ;Unix& quot; in the text to " ;UNIX. " This can be easily done in sed as follows: $ sed 's /Unix/ UNIX/' intro Substitute Unix with UNIX The UNIX operating system ... a particular string: $ sed -n ' /UNIX/ p' intro Just print lines containing UNIX The UNIX operating system was pioneered by Ken the design of the UNIX system was to c...

Ngày tải lên: 13/08/2014, 15:21

... equal to 100 , you can write result=$(( i >= 0 && i <= 100 )) which assigns result 1 if the expression is true and 0 if it's false: $ i=$(( 100 * 200 / 10 )) $ j=$(( i < 100 0 ... "What Is the Shell? ," you should realize that whenever you type something like who | wc -l that you are actually programming in the shell! That's because the shell i...

Ngày tải lên: 13/08/2014, 15:21

... foo1 :: :: x not known to foo1 or foo2 $ x =100 foo1 Try it this way :100 : x is known to foo1 :100 : and to its subshells $ echo :$x: :: Still not known to current shell $ Your PATH Return for a moment ... subsequently spawned subshells), the standard shell, /usr/bin/sh, is started. From that point on, this new shell processes commands typed in from the terminal. When Ctrl+d is type...

Ngày tải lên: 13/08/2014, 15:21

... 2 and then execute a subshell, which in turn executes other shell programs as subshells. If an interrupt signal is then generated, it will have no effect on the shells or subshells that are executing ... the subshells will be terminated. Suppose that you execute the command The IFS Variable There is a special shell variable called IFS, which stands for Internal Field Separator. The she...

Ngày tải lên: 13/08/2014, 15:21

... what shell to start up when you execute a shell escape. In such cases, you want to make sure that each time you start up a new shell, you get the shell you want and not an older Bourne shell. ... you to interactive features of the shell and two shells that have some nice features not found in the POSIX standard shell. Getting the Right Shell Most shells follow a convention...

Ngày tải lên: 13/08/2014, 15:21

... Read the last sed command into vi fc 100 110 Read commands 100 to 110 into $FCEDIT fc -s Re-execute the previous command fc -s abc=def 104 Re-execute command 104 , replacing abc with def The fg ... read hours mins 10 19 $ echo "$hours:$mins" 10: 19 $ read num rest 39 East 12th Street, New York City 100 03 $ echo "$num\n$rest" 39 East 12th Street, New York City 1...

Ngày tải lên: 13/08/2014, 15:21