shell script代做、代写c++设计、C/C++编程语言调试

日期：2020-05-05 11:17

1. Write a Bash shell script srclines.sh that accepts a

directory as its input and then displays the names of shell

scripts (.sh files) in the directory along with the number of

lines of code in it. The script should ignore lines with only

comments in it, as well as lines with no code in it (empty line

or lines with only spaces in it). For simplicity, you may assume

that the definition of "space" does not include tab characters.

The script should also display a totals for the number of shell

scripts and number of lines at the end.

Your shell script should display an appropriate error message

and terminate if it is not passed an argument or if the

arguments passed is not the name of a valid directory. The

script should also ignore any sub directories (as well as files

under them) that are inside the original directory passed as its

argument. If there are no shell scripts under the directory,

display that information as a message.

$ ./srclines.sh dir1

script1.sh 19

script2.sh 32

Total of 2 files with 51 lines of code

$

GRADING:

(i) 1 point for writing comments about logic throughout the

code (you need not include your personal information in the

beginning of the code).

(ii) 1 point for checking sufficient argument and displaying

messages.

(iii) 1 point for checking that the argument is valid (directory

and such), checking there are shell scripts in directory, etc.

(iv) 1 point for ignoring subdirectory structures.

(v) 6 points for executing the correct program logic.

2. Assume you are given the following c code:

#include <stdio.h>

#include <stdlib.h>

char *getInfo() {

char buffer[1000];

scanf("%s", buffer);

return buffer;

}

int main() {

char *ptr;

ptr = getInfo();

printf("%s\n", ptr); // <--- error

return 0;

}

The above code has an error identified at a particular line.

Assume no other lines of code have errors. Answer the

following questions:

(a) If you were using gdb to find the error, what commands

would you use? Write all the commands, including launching

gdb for the first time. Assume the executable is called a.out.

(b) Why is this line of code wrong?

Write you answer in gdb.txt.

3. (A) Write a C Program rev.c that reverses the argument

passed to it. You can assume that only one argument is

passed to the program. Your program must not use any arrays

(other than the one used to capture the arguments passed to

the main). You can ignore the situation where the program is

invoked without being passed an argument. Below is an

example of it's invocation.

$ ./rev Hello

olleH

$

(B) Now write a Bash shell script revname.sh that accepts a

filename as the argument and renames the file using the

above program. The script should throw an appropriate usage

message if it is not passed a filename argument. It should

also throw an appropriate error message if it cannot find the

filename passed as argument. If there is already a file with the

new name, then the script should throw an appropriate

message and not proceed. You may choose to ignore other

error situations and also assume that the file is in the current

directory. Following is an instance of a successful run of the

script.

$ ls

rev.c rev revname.sh main.c

$ ./revname.sh main.c

$ ls

rev.c rev revname.sh c.niam

$

Any error message displayed by your shell script must be from an

explicit echo command from your shell script, and not an error

message thrown by a command/statement you used in your script.

GRADING:

(A)

(i) 1 point for writing comments about logic throughout the

code (you need not include your personal information in the

beginning of the code).

(ii) 9 points for correctly performing the word checks.

(B)

(i) 1 point for writing comments about logic throughout the

code (you need not include your personal information in the

beginning of the code).

(ii) 1 point for checking sufficient/valid argument (file exists)

and displaying messages.

(iii) 3 points for checking the existence of target filename,

renaming the source file.

4. Write a modular C program having the following modules:

main.c and replace.c. The program will be invoked from the

command-line this way:

./update /bob/filename word1 word2

Construct a makefile that will compile the program in the

ways specified in this question and following proper modular

programming rules (for example using .h files and

implementing private/public).

In summary, the program does the following: it opens the text

file provided at the command-line and replaces all

occurrences of word1 by word2 from within the file. When the

program ends, the file's contents have changed (word1

occurrences are replaced by word2).

Do the following:

1. The arguments at the command line follow these rules: the

filename may or may not have a path, both word1 and word2

are single words without spaces and without special

characters like a punctuation. Assume the user inputs the

arguments correctly. Do not do data validation.

2. You are not permitted to load the entire file into memory.

You are not permitted to load an entire line of the file into

memory. You CAN read an entire word into memory or you

can read the file character by character.

3. You CAN write helper functions. You can open more than

one text file, if you want, but at the end only the original text

file must exist.

4. The module replace.c is responsible for detecting that the

word read from the file matches word1. If it does match

word1 then it returns word2, otherwise it returns word1.

5. The module main.c controls the file processing (reading

and writing to the file) and it calls the functions in replace.c,

receiving the return value of word2 or not.

6. The only libraries you can use are: math.h, string.h, stdio.h,

and stdlib.h, BUT only the functions covered during class. Do

not use other advanced functions not covered during the

lectures.

Git question: In addition to the above programming question,

assume this program uses git to backup the source files.

Assume further two developers were working together on this

program. Write the git commands to handle the following

case: developer 1 is editing replace.c, but developer 2 wants

to edit replace.c at the same time. (A) How can git help them

do this? (write the git commands), and (B) How can they

overcome a conflict, assuming the two replace.c files have a

git conflict? (write the git commands). Write your answer in

file git.txt.

GRADING:

(a) 5 points: modular programming and .h files

(b) 5 points: makefile

(c) 5 points: main.c module with optional main.h

(d) 5 points: replace.c module with optional replace.h

(e) 5 points: git question answer in git.txt