Input Redirection in the Shell

By BuckGup
December 10, 2019 in Linux, macOS and Everything Not-Windows

https://linustechtips.com/topic/1132882-input-redirection-in-the-shell/

Posted December 10, 2019

How exactly do I use input redirection in the shell. I have a file input.c

#include <stdio.h>

int main()
{
    char input[50];
    fgets(input, 50, stdin);
    printf("%s", input);
    return 0;
}

which just takes whatever you type and prints it out. I get how to use output redirection like

 ls -l > foo.txt

but I'm unsure how to or what input redirection is doing. Thanks

▓ƆԀ▓ S▓₱▓Ɇ▓c▓s▓: i7 6ʇɥפᴉƎ00K (4.4ghz), Asus DeLuxe X99A II, GT҉X҉1҉0҉8҉0 Zotac Amp ExTrꍟꎭe),Si6F4Gb D???????r PlatinUm, EVGA G2 Sǝʌǝᘉ5ᙣᙍᖇᓎᙎᗅᖶt, Phanteks Enthoo Primo, 3TB WD Black, 500gb 850 Evo, H100iGeeTeeX, Windows 10, K70 R̸̢̡̭͍͕̱̭̟̩̀̀̃́̃͒̈́̈́͑̑́̆͘͜ͅG̶̦̬͊́B̸͈̝̖͗̈́, G502, HyperX Cloud 2s, Asus MX34. פN∩SW∀S 960 EVO

Just keeping this here as a backup 9̵̨̢̨̧̧̡̧̡̧̡̧̡̡̢̢̡̢̧̡̢̡̡̢̧̛̛̛̛̛̛̱̖͈̠̝̯̹͉̝̞̩̠̹̺̰̺̲̳͈̞̻̜̫̹̱̗̣͙̻̘͎̲̝͙͍͔̯̲̟̞͚̖̘͉̭̰̣͎͕̼̼̜̼͕͎̣͇͓͓͎̼̺̯͈̤̝͖̩̭͍̣̱̞̬̺̯̼̤̲͎̖̠̟͍̘̭͔̟̗̙̗̗̤̦͍̫̬͔̦̳̗̳͔̞̼̝͍̝͈̻͇̭̠͈̳͍̫̮̥̭͍͔͈̠̹̼̬̰͈̤͚̖̯͍͉͖̥̹̺͕̲̥̤̺̹̹̪̺̺̭͕͓̟̳̹͍̖͎̣̫͓͍͈͕̳̹̙̰͉͙̝̜̠̥̝̲̮̬͕̰̹̳͕̰̲̣̯̫̮͙̹̮͙̮̝̣͇̺̺͇̺̺͈̳̜̣̙̻̣̜̻̦͚̹̩͓͚̖͍̥̟͍͎̦͙̫̜͔̭̥͈̬̝̺̩͙͙͉̻̰̬̗̣͖̦͎̥̜̬̹͓͈͙̤̜̗͔̩̖̳̫̑̀̂̽̈́̈́̿͒̿̋̊͌̾̄̄̒̌͐̽̿̊͑̑̆͗̈̎̄͒̑̋͛̑͑̂͑̀͐̀͑̓͊̇͆̿͑͛͛͆́͆̓̿̇̀̓͑͆͂̓̾̏͊̀̇̍̃́̒̎̀̒̄̓̒̐̑̊̏̌̽̓͂͋̓̐̓͊̌͋̀̐̇̌̓̔͊̈̇́̏͒̋͊̓̆̋̈̀̌̔͆͑̈̐̈̍̀̉̋̈́͊̽͂̿͌͊̆̾̉͐̿̓̄̾͑̈́͗͗̂̂́̇͂̀̈́́̽̈́̓̓͂̽̓̀̄͌̐̔̄̄͒͌̈́̅̉͊̂͒̀̈́̌͂̽̀̑̏̽̀͑̐̐͋̀̀͋̓̅͋͗̍́͗̈́̆̏̇͊̌̏̔̑̐̈́͑̎͑͆̏̎́̑̍̏̒̌̊͘͘̚̕̚̕̕̚̕̚̕̕͜͜͜͜͜͝͝͠͠͝͝͝͝͝͝͝͠͝͝ͅͅͅͅͅͅͅ8̵̨̛̛̛̛̮͍͕̥͉̦̥̱̞̜̫̘̤̖̬͍͇͓̜̻̪̤̣̣̹̑͑̏̈́̐̐́̎͒̔͒̌̑̓̆̓͑̉̈́́͋̌͋͐͛͋̃̍̽̊͗͋͊̂̅͊͑́͋͛̉̏̓͌̾̈́̀͛͊̾͑̌̀̀̌̓̏̑́̄̉̌͂́͛̋͊̄͐͊̈́̀̌̆̎̿̓̔̍̎̀̍̚̕̕͘͘͘̕̚͝͝͠͠͠0̶̡̡̡̢̨̨͕̠̠͉̺̻̯̱̘͇̥͎͖̯͕̖̬̭͔̪̪͎̺̠̤̬̬̤̣̭̣͍̥̱̘̳̣̤͚̭̥͚̦͙̱̦͕̼͖͙͕͇̭͓͉͎̹̣̣͕̜͍͖̳̭͕̼̳̖̩͍͔̱̙̠̝̺̰̦̱̿̄̀͐͜͜ͅͅt̶̡̨̡̨̧̢̧̢̨̧̧̧̧̢̡̨̨̢̨̢̧̢̛̛̛̛̛̠͍̞̮͇̪͉̩̗̗͖̫͉͎͓̮̣̘̫͔̘̬̮̙̯̣͕͓̲̣͓͓̣̹̟͈̱͚̘̼̙̖̖̼̙̜̝͙̣̠̪̲̞̖̠̯̖̠̜̱͉̲̺͙̤̻̦̜͎̙̳̺̭̪̱͓̦̹̺͙̫̖̖̰̣͈͍̜̺̘͕̬̥͇̗̖̺̣̲̫̟̣̜̭̟̱̳̳̖͖͇̹̯̜̹͙̻̥̙͉͕̜͎͕̦͕̱͖͉̜̹̱̦͔͎̲̦͔̖̘̫̻̹̮̗̮̜̰͇̰͔̱͙̞̠͍͉͕̳͍̰̠̗̠̯̜̩͓̭̺̦̲̲͖̯̩̲̣̠͉̦̬͓̠̜̲͍̘͇̳̳͔̼̣͚̙͙͚͕̙̘̣̠͍̟̪̝̲͇͚̦̖͕̰̟̪͖̳̲͉͙̰̭̼̩̟̝̣̝̬̳͎̙̱͒̃̈͊̔͒͗̐̄̌͐͆̍͂̃̈́̾͗̅̐͒̓̆͛̂̾͋̍͂̂̄̇̿̈͌̅̈́̃̾̔̇̇̾̀͊͋̋̌̄͌͆͆̎̓̈́̾̊͊̇̌̔̈́̈́̀̐͊̊̍͑̊̈̓͑̀́̅̀̑̈́̽̃̽͛̇́̐̓̀͆̔̈̀̍̏̆̓̆͒̋́̋̍́̂̉͛̓̓̂̋̎́̒̏̈͋̃̽͆̓̀̔͑̈́̓͌͑̅̽́̐̍̉̑̓̈́͌̋̈́͂̊́͆͂̇̈́̔̃͌̅̈́͌͛̑̐̓̔̈́̀͊͛̐̾͐̔̾̈̃̈̄͑̓̋̇̉̉̚̕̚͘̕̚̚̕̕͜͜͜͜͜͜͜͜͜͜͜͜͜͝͝͝͠͝͝͝͝͝͠ͅͅͅͅͅi̵̢̧̢̧̡̧̢̢̧̢̢̢̡̡̡̧̧̡̡̧̛̛͈̺̲̫͕̞͓̥̖̭̜̫͉̻̗̭̖͔̮̠͇̩̹̱͈̗̭͈̤̠̮͙͇̲͙̰̳̹̲͙̜̟͚͎͓̦̫͚̻̟̰̣̲̺̦̫͓̖̯̝̬͉̯͓͈̫̭̜̱̞̹̪͔̤̜͙͓̗̗̻̟͎͇̺̘̯̲̝̫͚̰̹̫̗̳̣͙̮̱̲͕̺̠͉̫̖̟͖̦͉̟͈̭̣̹̱̖̗̺̘̦̠̯̲͔̘̱̣͙̩̻̰̠͓͙̰̺̠̖̟̗̖͉̞̣̥̝̤̫̫̜͕̻͉̺͚̣̝̥͇̭͎̖̦̙̲͈̲̠̹̼͎͕̩͓̖̥̘̱̜͙̹̝͔̭̣̮̗̞̩̣̬̯̜̻̯̩̮̩̹̻̯̬̖͂̈͂̒̇͗͑̐̌̎̑̽̑̈̈́͑̽́̊͋̿͊͋̅̐̈́͑̇̿̈́̌͌̊̅͂̎͆̏̓͂̈̿̏̃͑̏̓͆̔̋̎̕͘͘͘͜͜͜͜͜͜͜͝͝͠͠ͅͅͅͅͅͅͅͅͅZ̴̧̢̨̢̧̢̢̡̧̢̢̢̨̨̨̡̨̧̢̧̛̛̬̖͈̮̝̭̖͖̗̹̣̼̼̘̘̫̠̭̞͙͔͙̜̠̗̪̠̼̫̻͓̳̟̲̳̻̙̼͇̺͎̘̹̼͔̺̹̬̯̤̮̟͈̭̻͚̣̲͔͙̥͕̣̻̰͈̼̱̺̤̤͉̙̦̩̗͎̞͓̭̞̗͉̳̭̭̺̹̹̮͕̘̪̞̱̥͈̹̳͇̟̹̱̙͚̯̮̳̤͍̪̞̦̳̦͍̲̥̳͇̪̬̰̠͙͕̖̝̫̩̯̱̘͓͎̪͈̤̜͎̱̹̹̱̲̻͎̖̳͚̭̪̦̗̬͍̯̘̣̩̬͖̝̹̣̗̭͖̜͕̼̼̲̭͕͔̩͓̞̝͓͍̗̙̯͔̯̞̝̳̜̜͉̖̩͇̩̘̪̥̱͓̭͎͖̱̙̩̜͎̙͉̟͎͔̝̥͕͍͓̹̮̦̫͚̠̯͓̱͖͔͓̤͉̠͙̋͐̀͌̈́͆̾͆̑̔͂͒̀̊̀͋͑̂͊̅͐̿́̈́̐̀̏̋̃̄͆͒̈́̿̎́́̈̀̀͌̔͋͊̊̉̿͗͊͑̔͐̇͆͛̂̐͊̉̄̈́̄̐͂͂͒͑͗̓͑̓̾̑͋̒͐͑̾͂̎̋̃̽̂̅̇̿̍̈́́̄̍͂͑̏̐̾̎̆̉̾͂̽̈̆̔́͋͗̓̑̕͘̕͘͜͜͜͜͜͝͝͝͝͠͠͝ͅo̶̪͆́̀͂̂́̄̅͂̿͛̈́̿͊͗́͘͝t̴̡̨̧̨̧̡̧̨̡̢̧̢̡̨̛̪͈̣̭̺̱̪̹̺̣̬̖̣̻͈̞̙͇̩̻̫͈̝̭̟͎̻̟̻̝̱͔̝̼͍̞̼̣̘̤̯͓͉̖̠̤͔̜̙͚͓̻͓̬͓̻̜̯̱̖̳̱̗̠̝̥̩͓̗̪̙͓̖̠͎̗͎̱̮̯̮͙̩̫̹̹̖͙̙͖̻͈̙̻͇͔̙̣̱͔̜̣̭̱͈͕̠̹͙̹͇̻̼͎͍̥̘͙̘̤̜͎̟͖̹̦̺̤͍̣̼̻̱̲͎̗̹͉͙̪̞̻̹͚̰̻͈͈͊̈́̽̀̎̃̊́̈́̏̃̍̉̇̑̂̇̏̀͊̑̓͛̽͋̈́͆́̊͊̍͌̈́̓͊̌̿̂̾̐͑̓̀́͒̃̋̓͆̇̀͊̆͗̂͑͐̀͗̅̆͘̕͘̕̕͜͜͝͝͝͝͝͝͝ͅͅͅͅͅͅͅͅͅḁ̶̢̡̨̧̡̡̨̨̧̨̡̡̢̧̨̡̡̛̛̛͍̱̳͚͕̩͍̺̪̻̫̙͈̬͙̖͙̬͍̬̟̣̝̲̼̜̼̺͎̥̮̝͙̪̘̙̻͖͇͚͙̣̬̖̲̲̥̯̦̗̰̙̗̪̞̗̩̻̪̤̣̜̳̩̦̻͓̞̙͍͙̫̩̹̥͚̻̦̗̰̲̙̫̬̱̺̞̟̻͓̞͚̦̘̝̤͎̤̜̜̥̗̱͈̣̻̰̮̼̙͚͚̠͚̲̤͔̰̭̙̳͍̭͎̙͚͍̟̺͎̝͓̹̰̟͈͈̖̺͙̩̯͔̙̭̟̞̟̼̮̦̜̳͕̞̼͈̜͍̮͕̜͚̝̦̞̥̜̥̗̠̦͇͖̳͈̜̮̣͚̲̟͙̎̈́́͊̔̑̽̅͐͐͆̀͐́̓̅̈͑͑̍̿̏́͆͌̋̌̃̒̽̀̋̀̃̏̌́͂̿̃̎̐͊̒̀̊̅͒̎͆̿̈́̑̐̒̀̈́̓̾͋͆̇̋͒̎̈̄̓̂͊̆͂̈́̒̎͐̇̍̆̋̅̿̔͒̄̇̂̋̈́͆̎̔̇͊̊̈́̔̏͋́̀͂̈́̊͋͂̍̾̓͛̇̔̚͘̚̕̚͘͘̕̕̕̚͘͘̚̕̚̕͜͜͜͝͝͝͝͝͝͝͝ͅͅͅͅͅç̵̧̢̨̢̢̢̧̧̡̨̡̢̧̧̧̨̡̡̨̨̢̢̢̧̨̢̨̢̛̛͉̗̠͇̹̖̝͕͚͎̟̻͓̳̰̻̺̞̣͚̤͙͍͇̗̼͖͔͕͙͖̺͙̖̹̘̘̺͓̜͍̣̰̗̖̺̗̪̘̯̘͚̲͚̲̬̞̹̹͕̭͔̳̘̝̬͉̗̪͉͕̞̫͔̭̭̜͉͔̬̫͙̖̙͚͔͙͚͍̲̘͚̪̗̞̣̞̲͎͔͖̺͍͎̝͎͍̣͍̩̟͈͕̗͉̪̯͉͎͖͍̖͎̖̯̲̘̦̟̭͍͚͓͈͙̬͖̘̱̝̜̘̹̩̝̥̜͎̬͓̬͙͍͇͚̟̫͇̬̲̥̘̞̘̟̘̝̫͈̙̻͇͎̣̪̪̠̲͓͉͙͚̭̪͇̯̠̯̠͖̞̜͓̲͎͇̼̱̦͍͉͈͕͉̗̟̖̗̱̭͚͎̘͓̬͍̱͍̖̯̜̗̹̰̲̩̪͍̞̜̫̩̠͔̻̫͍͇͕̰̰̘͚͈̠̻̮͊̐̿̏̐̀̇̑̐̈͛͑͑̍̑̔̃̈́̓̈́̇̐͑̐̊̆͂̀̏͛̊̔̍̽͗͋̊̍̓̈́̏̅͌̀̽́̑͒͒̓͗̈́̎͌͂̕̚͘͘͜͜͜͜͜͠͝͝͝͝ͅͅͅͅͅͅͅS̵̡̡̧̧̨̨̡̢̡̡̡̡̧̧̡̧̢̫̯͔̼̲͉͙̱̮̭̗͖̯̤͙̜͚̰̮̝͚̥̜̞̠̤̺̝͇̻̱͙̩̲̺͍̳̤̺̖̝̳̪̻̗̮̪̖̺̹̭͍͇̗̝̱̻̳̝̖̝͎̙͉̞̱̯̙̜͇̯̻̞̱̭̗͉̰̮̞͍̫̺͙͎̙̞̯̟͓͉̹̲͖͎̼̫̩̱͇̲͓̪͉̺̞̻͎̤̥̭̺̘̻̥͇̤̖̰̘̭̳̫̙̤̻͇̪̦̭̱͎̥̟͖͕̣̤̩̟̲̭̹̦̹̣͖̖͒̈́̈́̓͗̈̄͂̈́̅̐̐̿̎̂͗̎̿̕͘͜͜͜͜͝͝ͅͅt̸̡̡̧̧̨̡̢̛̥̥̭͍̗͈̩͕͔͔̞̟͍̭͇̙̺̤͚͎͈͎͕̱͈̦͍͔͓̬͚̗̰̦͓̭̰̭̎̀̂̈́̓̒̈́̈́̂̄̋́̇̂͐͒̋̋̉͐̉̏̇͋̓̈́͐̾͋̒͒͐̊̊̀̄͆̄͆̑͆̇̊̓̚̚̕̚̕͜͠͝͝ͅͅơ̵̡̨̡̡̡̨̛̺͕̼͔̼̪̳͖͓̠̘̘̳̼͚͙͙͚̰͚͚͖̥̦̥̘̖̜̰͔̠͕̦͎̞̮͚͕͍̤̠̦͍̥̝̰̖̳̫̮̪͇̤̱̜͙͔̯͙̙̼͇̹̥̜͈̲̺̝̻̮̬̼̫̞̗̣̪̱͓̺̜̠͇͚͓̳̹̥̳̠͍̫͈̟͈̘̯̬̞͔̝͍͍̥̒̐͗͒͂͆̑̀̿̏́̀͑͗̐́̀̾̓́̌̇̒̈́̌̓͐̃̈́̒̂̀̾͂̊̀̂͐̃̄̓̔̽̒̈́̇̓͌̇̂̆̒̏̊̋͊͛͌̊̇̒̅͌̄̎̔̈́͊́̽̋̈̇̈́́͊̅͂̎̃͌͊͛͂̄̽̈́̿͐̉̽̿́́̉͆̈́̒́̂̾̄̇̌̒̈̅̍̿̐͑̓͊̈́̈̋̈́̉̍̋̊̈̀̈́̾̿̌̀̈́͌̑̍́̋̒̀̂̈́́̾̏̐̅̈̑͗͐̈͂̄̾̄̈́̍̉͑͛͗͋̈́̃̄̊́́͐̀̀̽̇̓̄̓̃͋͋̂̽̔̀̎͌̈́̈́̑̓̔̀̓͐͛͆̿̋͑͛̈́͂̅̋̅͆͗̇́̀̒́̏͒̐̍͂̓͐͐̇̂̉̑̊͑̉̋̍͊̄̀͂̎͒̔͊̃̏̕̚̕̕͘͘͘̚͘̚͘̕͘̚͘̚̚̚̕͘͜͜͜͝͝͠͠͝͝͠͠͝͝͝͝͝͝͝͝͝ͅͅͅc̴̨̡̢̢̢̡̡̢̛̛̛̻͇̝̣͉͚͎͕̻̦͖̤̖͇̪̩̤̻̭̮̙̰̖̰̳̪̱̹̳̬͖̣͙̼̙̰̻̘͇͚̺̗̩̫̞̳̼̤͔͍͉̟͕̯̺͈̤̰̹̍̋́͆̾̆̊͆͋̀͑͒̄̿̄̀̂͋̊͆́͑̑̽͊̓́̔̽̌͊̄͑͒͐̑͗̿̃̀̓̅́̿͗̈́͌̋̀̏̂͌̓́̇̀͒͋̌̌̅͋͌̆͐̀̔̒͐̊̇̿̽̀̈́̃̒̋̀̈́̃̏̂̊͗̑̊̈̇̀̌͐̈́̉̂̏͊̄͐̈̽͒̏̒̓́̌̓̅́̓̃͐͊͒̄͑̒͌̍̈́̕͘̚͘̕͘̚̕͜͝͠͝͝͝ͅǩ̴̢̢̢̧̨̢̢̢̨̨̨̢̢̢̨̧̨̡̡̢̛̛̛̛̛̛̛̜̥̩̙͕̮̪̻͈̘̯̼̰̜͚̰͖̬̳͖̣̭̼͔̲͉̭̺͚̺̟͉̝̱̲͎͉̙̥̤͚͙̬̪̜̺͙͍̱̞̭̬̩̖̤̹̤̺̦͈̰̗̰͍͇̱̤̬̬͙̙̲̙̜͖͓̙̟̙̯̪͍̺̥͔͕̝̳̹̻͇̠̣͈̰̦͓͕̩͇͈͇̖͙͍̰̲̤̞͎̟̝̝͈͖͔͖̦̮̗̬̞̞̜̬̠̹̣̣̲̮̞̤̜̤̲̙͔͕̯͔͍̤͕̣͔͙̪̫̝̣̰̬̬̭̞͔̦̟̥̣̻͉͈̮̥̦̮̦͕̤͇̺͆͆̈͗̄̀̌̔̈́̈̉̾̊̐̆̂͛̀̋́̏̀̿͒̓̈́̈́͂̽̾͗͊̋̐̓̓̀̃̊̊͑̓̈̎̇͑̆̂̉̾̾̑͊̉̃́̑͌̀̌̐̅̃̿̆̎̈́̀̒́͛̓̀̊́̋͛͒͊̆̀̃̊͋̋̾̇̒̋͂̏͗͆̂̔́̐̀́͗̅̈̋̂̎̒͊̌̉̈̈́͌̈́̔̾̊̎́͐͒̋̽̽́̾̿̚̕͘͘̚̕̕̕̚̚̕̚̕͘͜͜͜͝͠͝͝͝͝͝͝͝͝ͅͅͅͅͅͅB̸̢̧̨̡̢̧̨̡̡̨̡̨̡̡̡̢̨̢̨̛̛̛̛̛̛͉̞͚̰̭̲͈͎͕͈̦͍͈̮̪̤̻̻͉̫̱͔̞̫̦̰͈̗̯̜̩̪̲̻̖̳͖̦͎͔̮̺̬̬̼̦̠̪̤͙͍͓̜̥̙̖̫̻̜͍̻̙̖̜̹͔̗̪̜̖̼̞̣̠̫͉̯̮̤͈͎̝̪͎͇͙̦̥͙̳̫̰̪̣̱̘̤̭̱͍̦͔̖͎̺̝̰̦̱̣͙̙̤͚̲͔̘̱̜̻͔̥̻͖̭͔̜͉̺͕͙͖̜͉͕̤͚̠̩̮̟͚̗͈͙̟̞̮̬̺̻̞͔̥͉͍̦̤͓̦̻̦̯̟̰̭̝̘̩̖̝͔̳͉̗̖̱̩̩̟͙͙͛̀͐̈́̂̇͛̅̒̉̏̈́̿͐́̏̃̏̓̌̽͐̈́͛̍͗͆͛̋̔̉͂̔̂̓̌͌͋̂͆̉͑̊̎́̈́̈̂͆͑́̃̍̇̿̅̾́́̿̅̾̆̅̈́̈̓͒͌͛̃͆̋͂̏̓̅̀͂̽̂̈̈́̎̾̐͋͑̅̍̈́̑̅̄͆̓̾̈́͐̎̊͐̌̌̓͊̊̔̈́̃͗̓͊͐̌͆̓͗̓̓̾̂̽͊͗́́́̽͊͆͋͊̀̑̿̔͒̏̈́́̏͆̈́͋̒͗͂̄̇̒͐̃͑̅̍͒̎̈́̌̋́̓͂̀̇͛̋͊͆̈́̋́̍̃͒̆̕̚̚̕̕̕͘̕̚̚͘̕͜͜͜͜͝͠͠͝͠͝͝͝͝͠͝͝͝͝ͅͅͅͅͅI̵̡̢̧̨̡̢̨̡̡̢̡̧̡̢̢̢̡̢̛̛͕͎͕̩̠̹̩̺̣̳̱͈̻̮̺̟̘̩̻̫͖̟͓̩̜̙͓͇̙̱̭̰̻̫̥̗̠͍͍͚̞̘̫͉̬̫̖̖̦͖͉̖̩̩̖̤̺̥̻̝͈͎̻͓̟̹͍̲͚͙̹̟̟̯͚̳̟͕̮̻̟͈͇̩̝̼̭̯͚͕̬͇̲̲̯̰̖̙̣̝͇̠̞̙͖͎̮̬̳̥̣̺̰͔̳̳̝̩̤̦̳̞̰̩̫̟͚̱̪̘͕̫̼͉̹̹̟̮̱̤̜͚̝̠̤̖̮̯̳͖̗̹̞̜̹̭̿̏͋̒͆̔̄̃̾̓͛̾̌́̅̂͆̔͌͆͋̔̾́̈̇̐̄̑̓̂̾́̄̿̓̅̆͌̉̎̏̄͛̉͆̓̎͒͘̕̕͜͜͜͜͜͜͜͝͠ͅͅƠ̷̛̛̛̛̛͋͂̅̈́̍͂̽͗̾͒̇̇̒͐̍̽͊́̑̇̑̾̉̓̈̾͒̍̌̅̒̾̈́̆͌̌̾̎̽̐̅̏́̈̔͛̀̋̃͊̒̓͗͒̑͒̃͂̌̄̇̑̇͛̆̾͛̒̇̍̒̓̀̈́̄̐͂̍͊͗̎̔͌͛̂̏̉̊̎͗͊͒̂̈̽̊́̔̊̃͑̈́̑̌̋̓̅̔́́͒̄̈́̈̂͐̈̅̈̓͌̓͊́̆͌̉͐̊̉͛̓̏̓̅̈́̕̕̕̚͘͘͘̚̕͝͝͝͠͝͝͝͝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Posted December 10, 2019

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I think I got it.

./input < chicken.txt

outputs

chicken

Inside chicken.txt is

chicken

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Posted December 10, 2019

In unix-like systems "everything is a file", including stdout. This means your program's output is "written" to stdout as though it were a normal text file. The ">" operator takes whatever file is on its left and writes its contents to the file on its right (and vice versa for "<") - so on the left of

ls -l > foo.txt

you have whatever "ls -l" has written to stdout and on the right you have a regular text file, meaning the content of stdout written by "ls -l" are now written to foo.txt.

In your other example, the contents of chicken.txt are being written to stdin which your program then reads. Note that the exact behavior of this is going to depend on your shell.

Don't ask to ask, just ask... please

sudo chmod -R 000 /*

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Posted December 10, 2019

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8 hours ago, Sauron said:
In unix-like systems "everything is a file", including stdout. This means your program's output is "written" to stdout as though it were a normal text file. The ">" operator takes whatever file is on its left and writes its contents to the file on its right (and vice versa for "<") - so on the left of
ls -l > foo.txt
you have whatever "ls -l" has written to stdout and on the right you have a regular text file, meaning the content of stdout written by "ls -l" are now written to foo.txt.

In your other example, the contents of chicken.txt are being written to stdin which your program then reads. Note that the exact behavior of this is going to depend on your shell.

Interesting, so when I am doing input redirection can I just type normally what I want or is this sort of redundant as I could of ran the program and used it normally? As redirected input would be more useful for taking input from a file to save time

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Posted December 10, 2019

22 minutes ago, BuckGup said:

Interesting, so when I am doing input redirection can I just type normally what I want or is this sort of redundant as I could of ran the program and used it normally? As redirected input would be more useful for taking input from a file to save time

It depends on what you want your program to do. If you want to process a file with a generic program that just reads stdin it makes sense to do it this way - it's the whole reason behind the "everything is a file" philosophy, you can chain together a bunch of programs that just read stdin to do whatever you want without worrying about where the input is coming from.

Another useful tool is piping