# Checksums

Another very common requirement for builds is generating checksums on your files. We've got you covered here now as well. Run `checksum help` for even more options.

## From the CLI

```
checksum file.txt
checksum path=build.zip algorithm=SHA-256
```

## From CFML

```javascript
command( 'checksum' )
    .params( 'file.txt' )
    .run();

command( 'checksum' )
    .params( path = 'build.zip', algorithm = 'SHA-256' )
    .run();
```

## Checksum all files in a directory

You can provide a file globbing pattern to receive a checksum for all files in a directory that match that pattern.

```
checksum *.cfc
```

## Output format

The `checksum` command also supports some other popular formats for outputting checksums. The default format is `checksum`.

```
checksum path=**.cfc format=checksum
checksum path=**.cfc format=sfv
checksum path=**.cfc format=md5sum
```

## Write out checksums

The `checksum` command will also write out a file that contains the hash which is a common requirement for builds that produce artifacts.

Write checksum(s) to a file named after the original file plus a new extension. This will create a file called `myFile.zip.md5`.

```
checksum myFile.zip md5 --write
```

Control the file extension like so. (`--write` is optional when supplying an extension) This will create a file called `myFile.zip.hash`.

```
checksum path=myFile.zip extension=hash --write
```

## Verify a file against an existing checksum

You can check a file against an existing checksum to make sure the file hasn't changed.

```
checksum path=myFile.zip verify=2A95F32028087699CCBEB09AFDA0348C
```