aws_vault prompt not working on macOS: date does not accept the options

[krissrex]

Environment: macOS Big Sur 11.6
Tl;dr: macOS has Unix date, bobthefish assumes Linux date.

---

There 2 problems:

theme-bobthefish/functions/fish_prompt.fish

Line 666 in 626bd39

set -l now (date --utc +%s)

theme-bobthefish/functions/fish_prompt.fish

Line 667 in 626bd39

set -l expiry (date -d "$AWS_SESSION_EXPIRATION" +%s)

Enabling the theme_display_aws_vault_profile results in:

date: illegal option -- -
usage: date [-jnRu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...
            [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

This is because date on macOS (unix) behaves differently from Linux:

date --utc +%s
date: illegal option -- -
usage: date [-jnRu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...
            [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

Potential solution:
I assume the -u flag works on a regular linux install. It also works on macOS:

date -u +%s
1633680739

---

theme-bobthefish/functions/fish_prompt.fish

Line 667 in 626bd39

set -l expiry (date -d "$AWS_SESSION_EXPIRATION" +%s)

Second problem: date does not like the -d flag.

date -d 2021-10-08T09:15:15Z +%s
usage: date [-jnRu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...
            [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

man date says the following (unix date):

-d dst Set the kernel's value for daylight saving time. If dst is non-zero, future calls to gettimeofday(2) will return a non-zero for tz_dsttime.

I did not find an appropriat option for this for mac's date.
However, macOS has gdate if coreutils are installed (brew install coreutils), and this works like linux's date.

So the fix may be to use gdate on macOS.

set -l now (gdate --utc +%s)
set -l expiry (gdate -d "$AWS_SESSION_EXPIRATION" +%s)

The best solution would not require installing anything extra.

---

Relevant on this topic: https://www.shell-tips.com/linux/how-to-format-date-and-time-in-linux-macos-and-bash/