What does /dev/sda means in Linux?

What /dev/ stand for?

All the device files are in /dev/ directory in Unix directory structure tree. Unix operating system treats everything as a file that we can access to read from and write to. /dev/ is the directory for devices.

What /sda stand for?

The word /sda has two parts.

sd:

It is originally identified a SCSI device. Initially only the SCSI devices were okay. But with the revolution USB and SATA devices Unix adopts it in the existing framework.

a:

Alphabetical order for the first found device. The first found device is sda. The second found device will be sdb. Similarly the 26th device will be sdz. If we have more device then the system would start from sdAa. Same way we as many devices we need.

What does sda1 means?

sda1 means the first partition on the first hard disk.

Other examples

sda2 = 2nd partition on the first hard disk
sdc8 = 8th partition on the third hard disk
sdb5 = 5th partition on the second hard disk

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