Final commit

Makefile

+myShell: myShell.c
+	gcc myShell.c -o myShell

README

+Type 'make' to get the executable of the shell.
+Name of the executable: myShell
+Name of the code file: myShell.c

myShell.c

+#include<stdio.h>
+#include<unistd.h>
+#include<string.h>
+#include<fcntl.h>
+#include<assert.h>
+#include<stdlib.h>
+#include<sys/wait.h>
+#include<signal.h>
+
+void driver(char command[], char in[], char out[], int inVal, int outVal, int AppVal);
+
+int readTotalCPU() {
+    char totalBuffer[200];
+    int totalFD = open("/proc/stat", O_RDONLY);
+    assert(totalFD != -1);
+
+    read(totalFD, totalBuffer, 200);
+    char *totalContent = strtok(totalBuffer, "\n");
+    totalContent += 5;
+    char *usage = strtok(totalContent, " ");
+    int total = 0;
+    while(usage != NULL) {
+        int temp;
+        sscanf(usage, "%d", &temp);
+        total += temp;
+        usage = strtok(NULL, " ");
+    }
+
+    close(totalFD);
+
+    return total;
+}
+
+void readProcCPU(char pid[], int *user, int *system) {
+    int utemp, stemp;
+    char path[20] = "/proc/";
+    char procContent[100];
+    strcat(path, pid);
+    strcat(path, "/stat");
+
+    char procBuffer[100];
+    int procFD = open(path, O_RDONLY);
+    assert(procFD != -1);
+    read(procFD, procBuffer, 100);
+
+    char *usage = strtok(procBuffer, " ");
+    int i=1;
+    while(usage != NULL) {
+        if(i==14) {
+            sscanf(usage, "%d", &utemp);
+        }
+        if(i==15) {
+            sscanf(usage, "%d", &stemp);
+            break;
+        }
+        usage = strtok(NULL, " ");
+        i++;
+    }
+
+    *user = utemp;
+    *system = stemp;
+
+    close(procFD);
+}
+
+void checkcpupercentage(char pid[]) {
+    int total1 = readTotalCPU();
+    int user1, system1;
+    readProcCPU(pid, &user1, &system1);
+
+    sleep(1);
+
+    int total2 = readTotalCPU();
+    int user2, system2;
+    readProcCPU(pid, &user2, &system2);
+
+    float userPerc, systemPerc;
+    float totalDiff = total2-total1;
+    float userDiff = user2-user1;
+    float systemDiff = system2-system1;
+    userPerc = userDiff/totalDiff*100;
+    systemPerc = systemDiff/totalDiff*100;
+
+    char temp[20], temp2[20];
+    sprintf(temp, "%f", userPerc);
+    sprintf(temp2, "%f", systemPerc);
+    char printUser[50] = "user mode cpu percentage: ";
+    char printSystem[50] = "system mode cpu percentage: ";
+    strcat(printUser, temp);
+    strcat(printUser, "\n");
+    write(1, printUser, 50);
+    strcat(printSystem, temp2);
+    strcat(printSystem, "\n");
+    write(1, printSystem, 50);
+}
+
+void checkresidentmemory(char pid[]) {
+    char *args[3];
+    args[0] = "ps";
+    args[1] = "-o";
+    args[2] = "rss=";
+    args[3] = pid;
+    args[4] = NULL;
+    execve("/bin/ps", args, NULL);
+}
+
+void listFiles() {
+    int fdLs = open("files.txt", O_CREAT | O_WRONLY, 0777);
+    dup2(fdLs, 1);
+    char *args[] = {"ls", NULL};
+    execve("/bin/ls", args, NULL);
+
+    close(fdLs);
+}
+
+void sortFile(char fileName[]) {
+    char *args[] = {"sort", fileName, NULL};
+    execve("/bin/sort", args, NULL);
+}
+
+void grepInput(char searchString[]) {
+    char *args[] = {"grep", "-a", searchString, NULL};
+    execve("/bin/grep", args, NULL);
+}
+
+void catInput(char file[]) {
+    char *args[] = {"cat", file, NULL};
+    execve("/bin/cat", args, NULL);
+}
+
+void executeCommands(char fileName[]) {
+    char *fileLines = malloc(10000*sizeof(char));
+    int fdExec = open(fileName, O_RDONLY);
+    read(fdExec, fileLines, 10000);
+    char *line = strtok(fileLines, "\n");
+    while(line!=NULL) {
+        int cc = fork();
+        if(cc>0) {
+            wait(NULL);
+        } else {
+            driver(line, NULL, NULL, 0, 0, 0);
+            exit(0);
+        }
+
+        line = strtok(NULL, "\n");
+    }
+
+    close(fdExec);
+    free(fileLines);
+}
+
+void handler(int sigNo) {
+    if(sigNo==SIGINT) {
+        write(1, "the program is interrupted, do you want to exit [Y/N]", 53);
+        char *d = (char*)malloc(sizeof(char));
+        read(0, d, 1);
+        if(*d=='Y') {
+            free(d);
+            exit(0);
+        }
+
+        free(d);
+    } else if(sigNo==SIGTERM) {
+        write(1, "Got SIGTERM-Leaving\n", 20);
+        exit(1);
+    }
+}
+
+void driver(char command[], char in[], char out[], int inVal, int outVal, int appVal) {
+    char *cmd = strtok(command, " ");
+    char *spid = strtok(NULL, "\n");
+    if(spid!=NULL) {
+        if(strstr(spid, " ") != NULL) {
+            spid = strtok(spid, " ");
+        }
+    }
+
+    if(appVal!=0) {
+        int fdApp = open(out, O_CREAT | O_WRONLY | O_APPEND, 0777);
+        dup2(fdApp, 1);
+    } else if(outVal!=0) {
+        int fdOut = open(out, O_CREAT | O_WRONLY, 0777);
+        dup2(fdOut, 1);
+    }
+
+    if(strstr(cmd, "checkcpupercentage")!=NULL) {
+        checkcpupercentage(spid);
+    } else if(strstr(cmd, "checkresidentmemory") != NULL) {
+        checkresidentmemory(spid);
+    } else if(strstr(cmd, "listFiles") != NULL) {
+        listFiles();
+    } else if(strstr(cmd, "sortFile") != NULL) {
+        if(inVal!=0) {
+            sortFile(in);
+        } else {
+            sortFile(spid);
+        }
+    } else if(strstr(cmd, "executeCommands") != NULL) {
+        if(inVal!=0) {
+            executeCommands(in);
+        } else {
+            executeCommands(spid);
+        }
+    } else if(strstr(cmd, "grep") != NULL) {
+        grepInput(spid);
+    } else if(strstr(cmd, "cat") != NULL) {
+        catInput(spid);
+    } else {
+        write(1, "Illegal command or arguments\n", 30);
+    }
+}
+
+void setInOut(char command[], char inVal[], char outVal[], int trailer, int *inP, int *outP, int *appP) {
+    char *out = strstr(command, ">");
+    char *in = strstr(command, "<");
+    char *app = strstr(command, ">>");
+    if(in != NULL) {
+        *inP = 1;
+        in += 2;
+        in = strtok(in, " ");
+        strcpy(inVal, in);
+    }
+    if(app!=NULL) {
+        *appP = 1;
+        app += 3;
+        app = strtok(app, "\n");
+        if(trailer) {
+            app = strtok(app, " ");
+        }
+        strcpy(outVal, app);
+    } else if(out != NULL) {
+        *outP = 1;
+        out += 2;
+        out = strtok(out, "\n");
+        if(trailer) {
+            out = strtok(out, " ");
+        }
+        strcpy(outVal, out);
+    }
+}
+
+void pipeDriver(char command[]) {
+    int pipeFD[2];
+    char *cmmd = strtok(command, "|");
+    char *cmmd2 = strtok(NULL, "\n");
+    cmmd2 += 1;
+    int inVal1=0, outVal1=0, appVal1=0, inVal2=0, outVal2=0, appVal2=0;
+    char in1[20], in2[20], out1[20], out2[20];
+    setInOut(cmmd, in1, out1, 1, &inVal1, &outVal1, &appVal1);
+    setInOut(cmmd2, in2, out2, 0, &inVal2, &outVal2, &appVal2);
+    if(pipe(pipeFD)==-1) {
+        write(1, "Error\n", 6);
+    }
+    int pc = fork();
+    if(pc>0) {
+        wait(NULL);
+        dup2(pipeFD[0], 0);
+        close(pipeFD[1]);
+        driver(cmmd2, NULL, out2, 0, outVal2, appVal2);
+        exit(0);
+    } else if(pc==0) {
+        dup2(pipeFD[1], 1);
+        close(pipeFD[0]);
+        driver(cmmd, in1, NULL, inVal1, 0, 0);
+        exit(0);
+    }
+}
+
+int main() {
+    while(1) {
+        struct sigaction sa;
+        sa.sa_handler = handler;
+        sigaction(SIGINT, &sa, NULL);
+        sigaction(SIGTERM, &sa, NULL);
+        write(1, "myShell> ", 10);
+        char *command = (char *)malloc(100*sizeof(char));
+        read(0, command, 100);
+        if(strstr(command, "exit")!=NULL) {
+            return 0;
+        }
+        if(strlen(command)==1)
+            continue;
+
+        int c = fork();
+        if(c > 0) {
+            wait(NULL);
+        } else if(c==0) {
+            if(strstr(command, " ; ") != NULL) {
+                char *cmmd = strtok(command, ";");
+                char *cmmd2 = strtok(NULL, "\n");
+                cmmd2 += 1;
+                int c2 = fork();
+                if(c2>0) {
+                    wait(NULL);
+                    char in[20], out[20];
+                    int inVal=0, outVal=0, appVal=0;
+                    setInOut(cmmd2, in, out, 0, &inVal, &outVal, &appVal);
+                    if(strstr(cmmd2, "|") != NULL) {
+                        pipeDriver(cmmd2);
+                    }
+                    else {
+                        driver(cmmd2, in, out, inVal, outVal, appVal);
+                    }
+                    exit(0);
+                } else if(c2==0) {
+                    char in[20], out[20];
+                    int inVal=0, outVal=0, appVal=0;
+                    setInOut(cmmd, in, out, 1, &inVal, &outVal, &appVal);
+                    if(strstr(cmmd, "|") != NULL) {
+                        pipeDriver(cmmd);
+                    } else {
+                        driver(cmmd, in, out, inVal, outVal, appVal);
+                    }
+                    exit(0);
+                }
+            } else {
+                char in[20], out[20];
+                int inVal=0, outVal=0, appVal=0;
+                setInOut(command, in, out, 0, &inVal, &outVal, &appVal);
+                if(strstr(command, "|") != NULL) {
+                    pipeDriver(command);
+                }
+                driver(command, in, out, inVal, outVal, appVal);
+                exit(0);
+            }
+
+            free(command);
+        }
+    }
+
+    return 0;
+}