How to convert Datetime to Unix timestamp in Tcl

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    # Human-readable date (2026-10-24 09:46:40)
    set date_string "2026-10-24 09:46:40"
    
    # Convert Date to Unix timestamp
    set unix_timestamp [clock scan $date_string -format "%Y-%m-%d %H:%M:%S" -gmt true]
    
    # Output the Unix timestamp
    puts "Unix Timestamp: $unix_timestamp"

Output:

Unix Timestamp: 1792835200

Example only. There may be multiple ways to perform this operation.

Code Explanation

In this TCL snippet clock scan $date_string takes the date string '2026-10-24 09:46:40' and converts it to a Unix timestamp. The -format "%Y-%m-%d %H:%M:%S" part tells TCL the format of the input string while -gmt true ensures that the date is interpreted in GMT (UTC).

Convert Unix timestamp to Date in TCL

Other useful Tcl date functions

Command	Description	Example
`clock format`	Formats a Unix timestamp into a human-readable date.	`clock format 1514764800 -format "%Y-%m-%d %H:%M:%S"` returns 2018-01-01 00:00:00
`clock scan`	Parses a date string and returns the Unix timestamp.	`clock scan "2018-07-15 12:30:45" -format "%Y-%m-%d %H:%M:%S"` returns 1531656645
`clock seconds`	Returns the current Unix timestamp.	`clock seconds` returns the current Unix timestamp.
`-gmt`	Used with `clock format` or `clock scan` to specify UTC (GMT) time.	`clock format 1514764800 -gmt true` formats the date in UTC.
`-format`	Specifies the format for parsing or displaying the date.	`clock format 1514764800 -format "%Y-%m-%d %H:%M:%S"` formats as 2018-01-01 00:00:00.

Current Unix Timestamp SECONDS SINCE JAN 01 1970

Current UTC Time

2025-08-20