scripting - Insert text between two marker lines in bash -

i have lines stored in text file called bashrc_snippet. insert them .bashrc. since change contents of text file able re-insert them in .bashrc-file. want use marker lines:

# user things histsize=1000  #start alias ls='ls --color=tty' ... more lines #end 

i bash script (possibly using sed or awk). algoritm should be:

• if marker lines missing add them @ end of file (and lines of text)
• if marker lines present, replace contents between them new lines of text

don't understand requirement, here's guess

#!/bin/bash  rcfile="$1" snippet="$2" var=$(<"$snippet") if grep -q "start" "$rcfile" ;then    awk -v v="$var" '/start/ {      print $0      print v      f=1    }f &&!/end/{next}/end/{f=0}!f' "$rcfile" >t && mv t "$rcfile" else    echo "#start" >> "$rcfile"    echo "$var" >> "$rcfile"    echo "#end" >> "$rcfile" fi 

to use:

$  ./test.sh rc_file bashrc_snippet