How can you run a command in bash over and over until success

Question

I have a script and want to ask the user for some information  but the script cannot continue until the user fills in this information  The following is my attempt at putting a command into a loop to achieve this but it doesn t work for some reason  echo  quot Please change password quot  while passwd do     echo  quot Try again quot  done  I have tried many variations of the while loop  while  passwd  while     quot  passwd  quot  -gt 0    while    passwd  -ne 0          And much more  But I can t seem to get it to work

User · Answer

If anyone looking to have retry limit   max retry 5 counter 0 until  command do    sleep 1       counter -eq  max retry     amp  amp  echo  Failed    amp  amp  exit 1    echo  Trying again  Try   counter       counter     done

User · Answer

You need to test    instead  which is the exit status of the previous command  passwd exits with 0 if everything worked ok  and non-zero if the passwd change failed  wrong password  password mismatch  etc      passwd while      -ne 0    do     passwd done   With your backtick version  you re comparing passwd s output  which would be stuff like Enter password and confirm password and the like

User · Answer

until passwd do   echo  Try again  done   or  while   passwd do   echo  Try again  done

User · Answer

You can use an infinite loop to achieve this   while true do   read -p  Enter password  passwd   case   passwd  in      lt some good condition gt    break     esac done

User · Answer

while   -n   passwd     do         echo  Try again   done

User · Answer

To elaborate on  Marc B s answer     passwd   while      -ne 0    do     done   Is nice way of doing the same thing that s not command specific

[bash] How can you run a command in bash over and over until success?

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