Indented lines (tree) to path-like lines

Question

I have input files with the structure like the next:

a1
  b1
    c1
    c2
    c3
  b2
    c1
      d1
      d2
  b3
  b4
a2
a3
  b1
  b2
    c1
    c2


        

Answer 1

I recently had to do something similar enough that with a few tweaks I can post my script here:

#!/bin/bash

prev_level=-1
# Index into node array
i=0

# Regex to screen-scrape all nodes
tc_re="^((  )*)(.*)$"
while IFS= read -r ln; do
    if  [[ $ln =~ $tc_re ]]; then
        # folder level indicated by spaces in preceding node name
        spaces=${#BASH_REMATCH[1]}
        # 2 space characters per level
        level=$(($spaces / 2))
        # Name of the folder or node
        node=${BASH_REMATCH[3]}        
        # get the rest of the node path from the previous entry
        curpath=( ${curpath[@]:0:$level} $node )

        # increment i only if the current level is <= the level of the previous
        # entry
        if [ $level -le $prev_level ]; then
            ((i++))
        fi

        # add this entry (overwrite previous if $i was not incremented)
        tc[$i]="${curpath[@]}"

        # save level for next iteration
        prev_level=$level
    fi
done

for p in "${tc[@]}"; do
    echo "${p// //}"
done

Input is taken from STDIN, so you'd have to do something like this:

$ ./tree2path.sh < ifile.tree 
a1/b1/c1
a1/b1/c2
a1/b1/c3
a1/b2/c1/d1
a1/b2/c1/d2
a1/b3
a1/b4
a2
a3/b1
a3/b2/c1
a3/b2/c2
$ 

Answer 2

interesting question.

this awk (could be one-liner) command does the job:

awk -F'  ' 'NF<=p{for(i=1;i<=p;i++)printf "%s%s", a[i],(i==p?RS:"/")
            if(NF<p)for(i=NF;i<=p;i++) delete a[i]}
            {a[NF] =$NF;p=NF }
            END{for(i=1;i<=NF;i++)printf "%s%s", a[i],(i==NF?RS:"/")}' file

you can see above, there are duplicated codes, you can extract them into a function if you like.

test with your data:

kent$  cat f
a1
  b1
    c1
    c2
    c3
  b2
    c1
      d1
      d2
  b3
  b4
a2
a3
  b1
  b2
    c1
    c2

kent$  awk -F'  ' 'NF<=p{for(i=1;i<=p;i++)printf "%s%s", a[i],(i==p?RS:"/")
if(NF<p)for(i=NF;i<=p;i++) delete a[i]}
{a[NF] =$NF;p=NF }END{for(i=1;i<=NF;i++)printf "%s%s", a[i],(i==NF?RS:"/")} ' f
a1/b1/c1
a1/b1/c2
a1/b1/c3
a1/b2/c1/d1
a1/b2/c1/d2
a1/b3
a1/b4
a2
a3/b1
a3/b2/c1
a3/b2/c2