How to find the latest folder in a directory and then make a full path accordingly?

I have a directory which will have some folders and some files within it. Suppose this is my current directory as shown below with pwd command –

david@slc4b03c:/bat/data/snapshot$ pwd
/bat/data/snapshot

And I am logged into machineA.

This /bat/data/snapshot directory will have some folders and some files within it as shown below –

david@slc4b03c:/bat/data/snapshot$ ls -lt
total 22400264
drwxr-xr-x 2 cronusapp app   102400 2013-12-22 04:01 20131222
drwxr-xr-x 2 cronusapp app   102400 2013-12-16 03:00 20131215
-rw-r--r-- 1 cronusapp app 26412620 2013-12-13 02:04 weekly_003_5.data
-rw-r--r-- 1 cronusapp app 26492037 2013-12-13 02:02 weekly_003_5.data
-rw-r--r-- 1 cronusapp app 26480695 2013-12-13 02:02 weekly_003_5.data
-rw-r--r-- 1 cronusapp app 26475266 2013-12-13 02:02 weekly_003_5.data
-rw-r--r-- 1 cronusapp app 26471366 2013-12-13 02:02 weekly_003_5.data
-rw-r--r-- 1 cronusapp app 26455311 2013-12-13 02:02 weekly_003_5.data

So the two folders I have is 20131222 and 20131215 as shown above.. Now I want to extract the latest folder from it, which will be 20131222 as it is more recent as compared to 20131215 and then make a full path like this –

/bat/data/snapshot/20131222/

As I need to use this full path while doing the scp from that machine to another machine,

Below is my shell script in which I have hardcoded the recent path currently with 20131222 but in general, I need to make the full path by seeing which folder is the latest one by using the below shell script..

#!/bin/bash

readonly LOCATION=/bat/data/snapshot

scp [e-mail]:/bat/data/snapshot/20131222/weekly_003_5.data /data01/primary/.

The above shell script I won’t be running from the machineA. I will be running from different machine, let’ say it is machineB.

Is it possible to do this in shell script?

Answer

Simple but unreliable solution

dir=$(ls -dt1 "$LOCATION"/*/ | head -n1)
scp "[e-mail]:$dir"/weekly_003_5.data /data01/primary/.

The above would fail if the name of the most recent directory contains a newline or other difficult characters.

If you want to restrict the directory name to be in the form of a date (YYYYMMDD), as per your examples, then try:

dir=$(ls -dt1 "$LOCATION"/[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]/ | head -n1)

For more info on the problems with using ls in this way, see:

• Why you shouldn’t parse the output of ls(1)

• Is there a reason why ls does not have a –zero or -0 option

• ls authors: “ls is really a tool for direct consumption by a human”

More Robust solution (GNU tools required)

This code uses find with NUL-separated output to handle difficult file names:

dir=$(find "$LOCATION" -mindepth 1 -maxdepth 1 -type d -printf '%T@ %p' |sort -znr | sed -zE 's/^[^ ]+ //;q')