function::tz_gmtoff - Linux

Overview

The tz_gmtoff command retrieves the offset of local time from Coordinated Universal Time (UTC) in seconds. This offset typically includes information about daylight saving time (DST). It is commonly used to adjust timestamps stored in UTC to the local time zone or to calculate the time difference between locations in different time zones.

Syntax

tz_gmtoff [--help]

Options/Flags

| Option | Description | Default |
|—|—|—|
| --help | Display usage information and exit | – |

Examples

Example 1: Get the UTC offset for the current time zone:

$ tz_gmtoff
-21600

Example 2: Adjust a UTC timestamp to local time:

$ date -d "$(date +%s) + 21600"
Tue Jan 10 18:00:00 PST 2023

Example 3: Calculate the time difference between two locations:

$ tz_gmtoff -3600 - 21600
-18000

Common Issues

Potential Error:

• tz_gmtoff: invalid time zone

Solution:

• Ensure that the time zone used as an input is valid.

Integration

Example Script:

The following script converts UTC timestamps in a file to local timestamps:

#!/bin/sh

# Get the UTC offset in seconds
utc_offset=$(tz_gmtoff)

# Convert the timestamps in the file
while read line
do
    timestamp=$(echo "$line" | cut -d' ' -f1)
    local_timestamp=$((timestamp + utc_offset))
    echo "$local_timestamp $(echo "$line" | cut -d' ' -f2-)"
done < input.txt

Related Commands

• date: Display or set the current date and time
• timezonectl: Manage system time zones