How to insert bash scripts inside the PS1 variable

Question

I made a custom PS1 variable, which is a tremendously confusing. Here is the one that is closest to being fully working:

PS1="\n[\e[1;31m]\u@\H[\e[35m] \@ [\e[32m] PWD: \w [\e[1;34m]This folder has \$(/bin/ls -1 | /usr/bin/wc -l | /bin/sed 's: ::g') files [\e[1;33m]A total of \$(/bin/ls -lah | /bin/grep -m 1 total | /bin/sed 's/total //')b\n`if [ \$? = 0 ]; then echo [\e[32m]^_^ [\e[0m] Worked - [\e[0m]; else echo [\e[31m]O_O[\e[0m]Didn't worked - ; fi`"

This is the same code as the previous code sample, but it has been separated into blocks and commented for better readability:

#User@Host [Red]
\n\[\e[1;31m\]\u@\H

#Hour [Purple]
\[\e[35m\] \@ 

#PWD [Green]
\[\e[32m\] PWD: \w 

#Number of files in PWD [Blue]
\[\e[1;34m\]This folder has \$(/bin/ls -1 | /usr/bin/wc -l | /bin/sed 's: ::g') files 

#Amount of space the PWD files take, also line break [Yellow]
\[\e[1;33m\]A total of \$(/bin/ls -lah | /bin/grep -m 1 total | /bin/sed 's/total //')b\n

#Malfunctioning condition, should smile if the instruction went right, or poker-face if not [green and red]
\`if [ \$? = 0 ]; then echo \[\e[32m\]^_^ \[\e[0m\]\[\e[0m\]Worked - \[\e[0m\]; else echo \[\e[31m\]O_O\[\e[0m\] Didn't worked - ; fi\`

Trying to explain the problem:

• if looks for a condition that can no longer be false after running for (eg.) "This folder has \$(/bin/ls -1 | /usr/bin/wc -l | /bin/sed 's: ::g') files", as it is true if the latest statement had a clean end.

How can I make it work while at same time keep the output in that same position? If the if is moved to before the first command executed, it works fine.

I thought of assigning a variable with that if condition at the start of the PS1. Then other if at this one's position would judge the alternative variable that would not change. But unfortunately I have no skill at all with Bash. I have already tried unsuccessfully to do it a thousand or so times.

Something like this (but well written):

PS1="`if [ \$? = 0 ];then echo "prev_err=0"; else prev_err=0; fi\` 
...[Some more code in between]...
`if [ \$prev_err = 0 ]
    then echo "No error"
    else echo "There was an error in the statement." 
fi\`"

Some ` (backtick characters) are in the wrong places or omitted in the previous code block.

Answer 1

You are probably better off doing most of that in PROMPT_COMMAND which, to quote the Bash manual "If set, the value is executed as a command prior to issuing each primary prompt"

See also this huge example.

Mine is :-

PROMPT_COMMAND='history -a; history -n; printf "\e]1;${PWD}\a"'

which keeps my history synched across terminal windows.

Then you should probably put as much of possible inside bash functions just to simplify the problem.

BTW - you might find du -sh . is a little more useful and easier than /bin/ls -lah | /bin/grep -m 1 total just to get the file usage`

Answer 2

My prompt contains several functions, such as

PS1='$(exit_code=$?; [[ $exit_code -eq 0 ]] || printf %s \[$BOLD_FORMAT\] \[$ERROR_FORMAT\] $exit_code \[$RESET_FORMAT\] " ")'

Does that work for you?