Bash提示使用if [$？ = 0]; 然后; else和/ $不按照它的意思运行

Question

I know I already had this running quite some time ago, but I haven't messed around with scripts and bash prompts for a long time an I am unable to come up with a solution.

I tried to use if [ $? = 0 ]; then; else;, in order to become a different prompt if a command provides an error and \\$, in order to get a #, in case root is logged in. I even came up with this nonsensical long prompt command:

PROMPT_COMMAND='if [ $? = 0 ]; then PS1="\[\e[31m\]║\[\033[04;35m\]\$(/bin/date)\[\e[00;32m\] History: \! \[\e[31m\]Jobs: \j \[\e[34m\]Status: \[\e[32m\]▇▇  ${debian_chroot:+($debian_chroot)}\n\[\033[31m\]║\[\e[33m\]\u@\[\e[37m\]\w/\[\e[32m\]\$:\[\e[0m\]"; else PS1="\[\e[31m\]║\[\033[04;35m\]\$(/bin/date)\[\e[00;32m\] History: \! \[\e[31m\]Jobs: \j \[\e[34m\]Status: \[\e[31m\]▇▇ ${debian_chroot:+($debian_chroot)}\n\[\e[31m\]║\[\e[33m\]\u@\[\e[37m\]\w/\[\e[32m\]\$:\[\e[0m\]"; fi'

I know the problem is that the if [ $? = 0 ]; then; else; portion works between "", while the /$ seems to work only between ''.

The funny thing is that this works ...

PS1="\`if [ \$? = 0 ]; then echo \[\e[33m\]^_^\[\e[0m\]; else echo \[\e[31m\]O_O\[\e[0m\]; fi\`[\u@\h:\w]\\$ "

while this doesn't (the if [ \\$? = 0 ]; then; else;) (\\$(/bin/date) and \\$ works this way)

PS1="\[\033[31m\]║\[\033[04;35m\]\$(/bin/date)\[\033[00;32m\] History: \! \[\033[31m\]Jobs: \j \`if [ \$? = 0 ]; then echo \[\e[34m\]Status: \[\e[32m\]▇▇; else echo \[\e[34m\]Status: \[\e[31m\]▇▇; fi\` ${debian_chroot:+($debian_chroot)}\n\[\033[31m\]║\[\033[33m\]\u@\[\033[37m\]\w/\[\033[32m\]\\$:\[\033[0m\]"

I'd like to keep both in my prompt, but I am obviously missing something (maybe because I was looking at this prompt too much. I would be glad to have a prompt that features \\$ and \\$(/bin/date), while changing if an error occurs, please help.

Cheers.

Answer 1

I recommend building your prompt from PROMPT_COMMAND , rather than trying to cram executable code into the value of PS1 itself. This makes the quoting simpler, as well as breaking the prompt into manageable pieces.

prompt_cmd () {
  exit_status=$?
  PS1='\[\e[31m\]║\[\e[04;35m\]\D{%+}'
  PS1+=' \[\e[32m\]History: \!'
  PS1+=' \[\e[31m\]Jobs: \j'
  PS1+=' \[\e[34m\]Status: '
  if [[ $exit_status = 0 ]]; then
    PS1+='\[\e[32m\]'
  else
    PS1+='\[\e[31m\]'
  fi
  PS1+='▇▇ '"${debian_chroot:+($debian_chroot)}"'\n'
  PS1+='\[\e[31m\]║\[\e[33m\]\u@\[\e[37m\]\w\[\e[32m\]\$:\[\e[0m\]'
}

PROMPT_COMMAND='prompt_cmd'