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3.6. Common parameter types

3.6.1. Quantity specifications

Values requiring large quantities may take a single 'k', 'm', 'g' or 't' suffix to multiply by 1,000, 1,000,000, 1,000,000,000 or 1,000,000,000,000 respectively. This may be used with a decimal point or trailing digits to specify a partial quantity, e.g. 9,600 may be specified as 9600, 9k6 or 9.6k.

Quantities involving disk space, memory or traffic volumes take 'k', 'm', 'g' and 't' to mean multiply by 1,024, 1,048,576, 1,073,741,824 and 1,099,511,627,776 respectively.

3.6.2. Interval specifications

Some parameters are specified as intervals. These parameters can be specified as integer numbers of seconds, or by using 'm', 'h', 'd' or 'w' as multipliers for minutes, hours, days or weeks respectively. Several multipliers can be used, e.g. 1h30m specifies one hour and thirty minutes.

Note that when scheduling, this model is extended so that when the interval is an exact multiple of a day, the interval is treated as days aligned at midnight local time rather than seconds, as seconds truncated to a multiple of 24 hours would result in days aligned at midnight GMT, not midnight local time. Note that this means that when daylight saving starts and ends, a "day" can be 23 or 25 hours (assuming a one hour daylight saving offset). The day number calculation is arranged so that if 7 days is requested, the week starts at midnight Monday morning.

Additionally, if a multiple of 30 days is requested, it is treated as actual calendar months, not intervals of 30 days. That is, an interval of 90 days would indicate periods starting on 1 January, 1 April, 1 July and 1 October.

3.6.3. Time-based file names

Output file names (including data files, log files etc) may be specified containing time component substitution strings corresponding with those provided by the Unix strftime() library call. The time applied, for data files, is the start time of the sample being written, while for log files, the time the file is opened is used.

For example, to output files in the form out-YYYYMMDD-HHMM.dat, one could use out-%Y%m%d-%H%M.dat.

Common time substitution strings include:

For more information, see ref man-strftime strftime(3) format specifiers.


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