Cisco "show flash" Command Explained
show flash — lists the files stored in a Cisco device's flash memory — IOS images, configuration backups, and available free space. Runs in privileged EXEC mode.
Syntax and common variants
| Variant | Purpose |
|---|---|
show flash | List files and free space in flash |
dir flash: | The modern IOS-preferred equivalent |
show file systems | List all available storage (flash, NVRAM, etc.) |
Reading the output
| Output / element | Meaning |
|---|---|
Filename | IOS image or other stored file |
Size (bytes) | File size |
bytes total / bytes free | Available flash capacity — critical before an upgrade |
When to use it
The essential pre-flight check before any IOS upgrade: is there enough free flash space for the new image? Also used to confirm an uploaded image actually landed correctly (via TFTP) before attempting to boot from it. Browse more in the command reference or practise in the free labs.
Frequently asked questions
Why check show flash before an upgrade?
To confirm enough free space exists for the new IOS image — attempting to copy an image that doesn't fit fails partway through, potentially leaving a corrupted file.
What is the difference between show flash and dir flash:?
They report similar information; dir flash: is the more modern, generalized command that also works across different storage types.
What do I do if flash is full before an upgrade?
Delete old, unused IOS images or backup files from flash (after confirming they're not needed) to free enough space for the new image.
Related articles
Want hands-on training?
Learn this on real Cisco lab devices with placement support at Attila Technologies, Ahmedabad.