Is 'yum check-update' mandatory to do an update?

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1

For Fedora Workstation 36. About yum (yes I know it is replaced by dnf) - I am using yum for academic purposes.

To accomplish an update of all the packages available in the OS - is used the sudo yum update command - I want to know if is necessary/mandatory execute first the yum check-update command. I know it shows all the new data available for update purposes, but I am not sure if only does that job - I mean:

For example in Ubuntu the following is mandatory

# [Mandatory] Retrieves all the new data available for the OS
sudo apt update
# [Optional]  Shows all the new data available for the OS, 
#             it depends of the previous command execution
     apt list --upgradable  
# [Mandatory] Update all the new data available for the OS,
#             The first command must be executed before.
sudo apt upgrade

So I am not sure if sudo yum update does two jobs - first retrieve the info about all the new data available and second proceeds to accomplish the update. Therefore consider the 2 following scenarios:

Case 1

sudo yum update

Case 2

     yum check-update
sudo yum update

What is the correct case for Fedora? Case 1 o 2?

2

This is correct. yum check-update is not necessary.

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3

Also noting here: yum is now deprecated, please use dnf. (yum will just call dnf now, it should just be a symlink to dnf)

You can see what the different commands do in the dnf manual: man dnf.

4

Yum as a separate command no longer exists, so for academic purposes it is out of date and really should be replaced with its successor, dnf. The only time it is relevant is when those versions of fedora where it was in use before dnf was introduced are the active OS.

In fact if you run ls -l /usr/bin/yum you will see that it is a symlink to dnf-3 with both fedora 35 and 36.

With regard to your original question, in fact, if you do man dnf and read the text you will see this.

  Upgrade Command
       Command: upgrade
       Aliases: up
       Deprecated aliases: update, upgrade-to, update-to, localupdate

so it seems reasonable that (for academic purposes) to use yum update is really also out of date since ‘update’ is a deprecated alias for ‘upgrade’ and the upgrade command will not likely disappear but update might.

YOu could have answered your own question with yum check-update --help which returns

$ yum check-update --help
-------------------
check for available package upgrades

and man dnf which shows

   Check-Update Command
       Command: check-update
       Aliases: check-upgrade

       dnf [options] check-update [--changelogs] [<package-file-spec>...]
          Non-interactively  checks  if  updates  of  the specified packages are available. If no <package-file-spec> is given,
          checks whether any updates at all are available for your system. DNF exit code will be 100  when  there  are  updates
          available  and  a  list  of the updates will be printed, 0 if not and 1 if an error occurs. If --changelogs option is
          specified, also changelog delta of packages about to be updated is printed.

          Please note that having a specific newer version available for an installed package (and  reported  by  check-update)
          does not imply that subsequent dnf upgrade will install it. The difference is that dnf upgrade has restrictions (like
          package dependencies being satisfied) to take into account.

          The output is affected by the autocheck_running_kernel configuration option.
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5

Thanks for the replies, and according with them

This is correct. yum check-update is not necessary.

Ok, understood, it is similar than apt list --upgradable - it how a simple comparison

Also noting here: yum is now deprecated, please use dnf . ( yum will just call dnf now, it should just be a symlink to dnf )

Agree, just using yum for academic purposes.

Yum as a separate command no longer exists, so for academic purposes it is out of date and really should be replaced with its successor, dnf

I understand, but I assumed it should not harm the OS itself. According with a new research - being correct that dnf replaces yum - so far: " yum will just call dnf now, it should just be a symlink to dnf" - it according with a previous answer of your answer)

In fact if you run ls -l /usr/bin/yum you will see that it is a symlink to dnf-3 with both fedora 35 and 36.

Yes, correct, confirmed for FW 36.

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