How to add the output of a command to the Bash prompt?
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| Project: | Linux software |
| Component: | Documentation |
| Category: | feature request |
| Priority: | normal |
| Assigned: | Unassigned |
| Status: | active |
| Related pages: | #5655: French Republican Calendar :-:-: #5663: bash prompt |
| Tags: | bash prompt |
Description
How to get the output of a command within the bash prompt?
I tried something simply like the following, but the time is not being updated. The times is obviously only calculated once, when PS1 is being evaluated:
$ PS1="$(date +%H:%M:%S) $ "
18:42:27 $
18:42:27 $
18:42:27 $
18:42:27 $
18:42:27 $
18:42:27 $
18:42:27 $ PS1="$(date +%H:%M:%S) $ "
18:42:45 $ How to make it so that the command is being evaluated each time?
I now I can use \t for the current time, but above is only an example. I actually want something like the following output:
$ PS1="$(t=`date +%s` ; let t=t+8*3600; perl -MDateTime::Calendar::FrenchRevolutionary -le "print DateTime::Calendar::FrenchRevolutionary->from_epoch(epoch => $t)->strftime('%c')") > "
Tri 23 Plu 0224 7:84:62 >
Tri 23 Plu 0224 7:84:62 >
Tri 23 Plu 0224 7:84:62 >
Tri 23 Plu 0224 7:84:62 >
Tri 23 Plu 0224 7:84:62 >
Tri 23 Plu 0224 7:84:62 >
Tri 23 Plu 0224 7:84:62 >
Tri 23 Plu 0224 7:84:62 >
Tri 23 Plu 0224 7:84:62 >
Tri 23 Plu 0224 7:84:62 >
Tri 23 Plu 0224 7:84:62 > PS1="$(t=`date +%s` ; let t=t+8*3600; perl -MDateTime::Calendar::FrenchRevolutionary -le "print DateTime::Calendar::FrenchRevolutionary->from_epoch(epoch => $t)->strftime('%c')") > "
Tri 23 Plu 0224 7:85:17 >
Tri 23 Plu 0224 7:85:17 >
Tri 23 Plu 0224 7:85:17 >
Tri 23 Plu 0224 7:85:17 >
Tri 23 Plu 0224 7:85:17 >
Comments
#1
Oh! The answer is easy. Simply escape the $ thus: \$
$ PS1="\$(date +%H:%M:%S) $ "18:52:32 $
18:52:33 $
18:52:34 $
18:52:34 $
18:52:36 $
#2
There was some escaping problem with the long command, so the easiest is to create a function:
$ function french_republican_time { t=`date +%s` ; let t=t+8*3600; perl -MDateTime::Calendar::FrenchRevolutionary -le "print DateTime::Calendar::FrenchRevolutionary->from_epoch(epoch => $t)->strftime('%c')"; }$ PS1="\$(french_republican_time) $ "
Tri 23 Plu 0224 7:89:90 $
Tri 23 Plu 0224 7:89:90 $
Tri 23 Plu 0224 7:89:91 $
Tri 23 Plu 0224 7:89:92 $