Sfrgttk

I usually do

sleep 4h; command

to execute a command after 4h. However, if that command requires sudo, it'll not work.

Is it possible to give sudo permission at the moment I'm running the sleep command?

Use sudo to start a root shell where you run the commands:

sudo bash -c 'sleep 4h; command'

Every command running in the root shell runs with root permissions, which for sleep doesn’t hurt. If you need to run a command with user permissions in it use sudo -u USERNAME COMMAND, e.g.:

$ sudo bash -c 'sleep 4h; sudo -u dessert whoami; whoami'

dessert  # whoami run as user dessert

root     # whoami run as root

Another approach would be to use sudo visudo to allow the command’s execution without root access, see:
How to allow execution without prompting for password using sudo?

Note that depending on the command this may create a security flaw.

Assuming you only want to run the process once (not, e.g. every 4 hours) then you can use atd

1. Ensure that atd is running (in ubuntu that is normally /etc/init.d/atd status
   


2. 
   

   At a terminal as root run your command as follows:

   
   
   

   # at now + 4 hours
warning: commands will be executed using /bin/sh
at> command
at> CTRL-D

   
   


3. 
   

   If you want to run it every 4 hours you could also use cron (as root) with the following config in your crontab

   
   
   

   0 */4 * * * sh -c $'/path/to/command'

   
   

One way is to run via a shellscript with sudo permissions (and give the password, when you start the shellscript), if the shellscript is in the current directory,

sudo ./delayer 4h

where delayer can be a shellscript with the content

#!/bin/bash

sleep "$1"

command

Make it executable with

chmod +x delayer

and copy or move it to a directory in PATH if you wish.

If you want a more flexible shellscript, where you can select the command [line] to delay by entering parameter(s), you can try

#!/bin/bash



if [ $# -lt 2 ] || [ "$(whoami)" != "root" ]

then

 echo "Delay start of command, that needs 'sudo'

Usage:    sudo $0 <delay> <command line>

Example:  sudo $0 4h parted -ls"

 exit

fi



sleep "$1"

shift

"$@"

Demo example (short delay, 5s, for demo purpose),

$ ./delayer

Delay start of command, that needs 'sudo'

Usage:    sudo ./delayer <delay> <command line>

Example:  sudo ./delayer 4h parted -ls



$ sudo ./delayer 5s parted /dev/sdc p

[sudo] password for sudodus: 

Model: Kanguru SS3 (scsi)

Disk /dev/sdc: 15,9GB

Sector size (logical/physical): 512B/512B

Partition Table: gpt

Disk Flags: 



Number  Start   End     Size    File system  Name     Flags

 2      1049kB  2097kB  1049kB               primary  bios_grub

 3      2097kB  258MB   256MB   fat32        primary  boot, esp

 4      258MB   2274MB  2016MB               primary

 5      2274MB  12,5GB  10,2GB  ext2         primary

 1      12,5GB  15,9GB  3394MB  ntfs         primary  msftdata

The best practice is

sudo bash -c 'sleep 4h; command'

That's all fit in your answer without any bash scripting or cron

Another way would be to start sudo interactive session with sudo -s (does not change directory) or sudo -i (changes current directory to root home directory) and then enter your commands (without sudo)