Question

I try to filter the system log by running the sed command
like:

error
    info_a1
    info_a2
    info_a3
crit
    info_b 
error
    info_c1 
    info_c2
warn
    info_d 
error
    info_x 
error
    info_p 
info
    info_w 
error
    info_z1 
    info_z2

I expect to get all the error messages like：

error 
    info_a1
    info_a2
    info_a3 
error
    info_c1 
    info_c2
error
    info_x 
error
    info_p
error
    info_z1 
    info_z2

i use

sed -n “/error/, /[info|warn|crit|]/p”

but it does not work pretty well.

Answer 1

awk '
  /^error/ {p=1}
  /^(info|warn|crit)/ {p=0}
  p
'