#include

#include

#include

#include

#include

#include

#include

#include

using namespace std;

void executeCommand$($const vector& args$)$;

vector parseInput$($string input$)$;

void printCpuClockSpeed$()$;

int main$()\{$

string input;

string prompt $=$ "cwushell$>"$;

vector args;

while $($true$)\{$

cout $$ prompt ;

getline$($cin$,$ input$)$;

args $=$ parseInput$($input$)$;

if $($args$.$empty$())\{$

continue;

$\}$

$//$ Internal command: exit

if $($args$[0]==$ "exit"$)\{$

int exitStatus $=$ args.size$()>1?$ stoi$($args$[1])$ : $0$;

exit$($exitStatus$)$;

$\}$

$//$ Internal command: prompt

else if $($args$[0]==$ "prompt"$)\{$

if $($args$.$size$()>1)\{$

prompt $=$ args$[1]$;

$\}$ else $\{$

prompt $=$ "cwushell$>"$;

$\}$

$\}$

$//$ Internal command: cpuinfo

else if $($args$[0]==$ "cpuinfo"$)\{$

if $($args$.$size$()>1)\{$

if $($args$[1]=="-$c$")\{$

printCpuClockSpeed$()$;

$\}$ else if $($args$[1]=="-$t$")\{$

$//$ Print CPU type

$\}$ else if $($args$[1]=="-$n$")\{$

$//$ Print number of CPU cores

$\}$ else $\{$

cout $$ "Invalid switch for cpuinfo" $$ endl;

$\}$

$\}$ else $\{$

cout No switch provided for cpuinfo" $$ endl;

$\}$

$\}$

$//$ Internal command: meminfo

else if $($args$[0]==$ "meminfo"$)\{$

$//$ Similar to cpuinfo

$\}$

$//$ External commands

else $\{$

executeCommand$($args$)$;

$\}$

$\}$

return $0$;

$\}$

void printCpuClockSpeed$()\{$

ifstream file$("/$proc$/$cpuinfo$")$;

if $(!$file.is$\_$open$())\{$

cerr $$ "Error opening file: $"$ strerror$($errno$)$ endl;

return;

$\}$

string line;

while $($getline$($file$,$ line$))\{$

if $($line$.$find$("$cpu MHz$")!=$ string::npos$)\{$

$//$ Process the line to extract CPU speed

$//$ The line typically looks like "cpu MHz : $2400\mathrm{.}000"$

size$\_$t pos $=$ line.find$("$:$")$;

if $($pos $!=$ string::npos$)\{$

string speedStr $=$ line.substr$($pos $+1)$;

double speedMHz $=$ stod$($speedStr$)$;

cout $$ "CPU Clock Speed: $"$ speedMHz MHz$"$ endl;

$\}$

break;

$\}$

$\}$

file.close$()$;

$\}$

vector parseInput$($string input$)\{$

vector args;

string arg;

istringstream iss$($input$)$;

while $($iss $>>$ arg$)\{$

args.push$\_$back$($arg$)$;

$\}$

return args;

$\}$

void executeCommand$($const vector& args$)\{$

pid$\_$t pid $=$ fork$()$;

if $($pid $==-1)\{$

perror$("$fork$")$;

$\}$ else if $($pid $==0)\{$

$//$ Convert vector to char$*$ array for execvp

vector c$\_$args;

for $($const auto& arg : args$)\{$

c$\_$args.push$\_$back$($const$\_$cast$($arg$.$c$\_$str$()))$;

$\}$

c$\_$args.push$\_$back$($nullptr$)$;

execvp$($c$\_$args$[0],$ c$\_$args.data$())$;

perror$("$execvp$")$;

exit$($EXIT$\_$FAILURE$)$;

$\}$ else $\{$

wait$($nullptr$)$; $//$ Wait for the child process to finish

$\}$

$\}$