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Understanding strftime()

Understanding strftime()#

NeoMutt uses the C library function strftime() to format dates and times wherever a date format string is expected — most commonly in $index_format, $date_format, and conditional date expressions.

How NeoMutt Uses strftime()#

In NeoMutt’s format strings, date expandos like %{...}, %[...], and %(...) pass their contents to strftime() for expansion:

Expando

Meaning

%{fmt}

Message date/time converted to the sender’s time zone

%[fmt]

Message date/time converted to the local time zone

%(fmt)

Date/time when the message was received locally

The fmt part inside the braces is a strftime() format string.

Common Format Codes#

Code

Description

Example

%Y

Year with century

2026

%y

Year without century

26

%m

Month (01–12)

04

%b

Abbreviated month name

Apr

%B

Full month name

April

%d

Day of month (01–31)

04

%a

Abbreviated weekday name

Sat

%A

Full weekday name

Saturday

%H

Hour, 24-hour (00–23)

15

%I

Hour, 12-hour (01–12)

03

%M

Minute (00–59)

07

%S

Second (00–60)

42

%p

AM or PM

PM

%Z

Time zone abbreviation

CET

%z

UTC offset

+0100

%F

ISO 8601 date (%Y-%m-%d)

2026-04-04

%T

ISO 8601 time (%H:%M:%S)

15:07:42

%c

Locale’s date and time

Sat Apr  4 15:07:42 2026

%%

Literal %

%

Examples in NeoMutt#

Setting the date format#

set date_format = "%d/%m/%y %H:%M"

This makes the %d expando in $index_format display dates like 04/04/26 15:07.

Using date expandos in index_format#

set index_format = "%4C %Z %[%b %d %H:%M] %-15.15L %s"

Here %[%b %d %H:%M] formats the message date in the local time zone as Apr 04 15:07.

Combining with conditional dates#

NeoMutt’s conditional date feature uses strftime() codes inside the true/false branches:

set index_format = '%4C %Z %<[d?%[%H:%M]&%[%b %d]> %-15.15L %s'

Today’s messages show the time (15:07), older messages show month and day (Apr 04).

Locale Dependence#

The output of codes like %a, %b, %B, and %c depends on the current locale. NeoMutt inherits the locale from your environment — the LC_TIME environment variable controls which locale strftime() uses.

Further Reading#