As a in-shell solution, you can loop through filenames, and search and print out the one with the largest number. In bash:
Code:
last=0
for file in energy.dat.[0-9]* ; do
(( ${file//[^0-9]} > ${last//[^0-9]} )) && last=$file
done
echo "$last"
This example assumes that there's only a single set of non-zero-padded* digits in each files, as ${file//[^0-9]} simply removes everything else. But it should be easily modifiable for other patterns.
(*most shells treat integers with leading zeros as octal values when doing arithmetic operations. )
Speaking of zero-padding, the real best way to handle it, in my opinion, is to simply make sure all the numbers are zero-padded to the same number of digits first. Then the shell will sort them for you automatically, and you can simply use whichever technique you want to grab the last value in the list.
Add all the names to an array, for example, and use the final entry.
Code:
files=( energy.dat.[0-9]* )
echo "${files[-1]}" #bash 4.2+ allows negative indexing
echo "${files[@]: -1}" #for earlier versions
I wrote this script a while ago that zero-pads numbers in file names. You can give it a try.
Code:
#!/bin/bash
# Pads numbers in file names if found.
# See help message for more.
# Set the environment
shopt -s extglob
IFS=""
BCYAN="${BCYAN:-\e[1;36m}" #Define some color codes, for prettified output.
#BGREEN="${BGREEN:-\e[1;32m}" #Use environment defaults if they exist.
#BRED="${BRED:-\e[1;31m}"
#BBLUE="${BBLUE:-\e[1;34m}"
#BMAGENTA="${BMAGENTA:-\e[1;35m}"
RESET="${RESET:-\e[0m}"
#set default padding level
pad=2
# Set up the help dialog
help+=( '' )
help+=( '\tA quick script to zero-pad files that contain numbers.' )
help+=( '\tIt will only pad the first number string it finds in the name, and ignores files without numbers.' )
help+=( '' )
help+=( "\tUsage: \t${BCYAN}${0##*/} [-n <num>] <files>${RESET}" )
help+=( "\t\t${BCYAN}${0##*/} -h${RESET}" )
help+=( '' )
help+=( '\tUse -n to specify the number of digits to pad, from 1-9. Defaults to '"$pad"' if not used.' )
help+=( '\tIf no files are given, it processes the current directory.' )
help+=( '' )
# Process input options
# If "-h" print help & exit.
# If "-n" test for valid inputs and set "pad" variable
# Ignore anything else
while getopts ":hn:" opt; do
case "$opt" in
h) IFS=$'\n'
echo -e "${help[*]}" >&2
exit "2"
;;
n) if [[ "$OPTARG" =~ [^[:digit:]] ]] || (( "10#$OPTARG" < 1 )) || (( "10#$OPTARG" > 9 )); then
echo
echo -e "${BCYAN}invalid option: [$OPTARG].${RESET}" >&2
echo -e "${BCYAN}-n must be an integer from 1 to 9${RESET}" >&2
echo -e "${BCYAN}Falling back to the default of $pad${RESET}"
echo
else
pad="$(( 10#$OPTARG ))"
fi
;;
\?) echo -e "${BCYAN}Invalid option: [-$OPTARG]. Ignoring.${RESET}" >&2
;;
esac
done
shift $(( OPTIND - 1 )) ; OPTIND=1
# Now test for files.
# If nothing given, set input parameters to files in current directory.
if [[ -z "$*" ]]; then
set -- ./*
fi
# Process files in input parameters
for file in "$@" ; do
# Ignore files without digits
[[ "$file" != *[0-9]* ]] && continue
# Split filename into prefix-digits-suffix
[[ "$file" =~ ([^[0-9]*)([0-9]+)(.*) ]]
# Pad digits to desired width
printf -v numpad "%0*d" "$pad" "${BASH_REMATCH[2]##*(0)}"
# Add old and new filenames to arrays for final processing
oldfile+=( "$file" )
newfile+=( "${BASH_REMATCH[1]}${numpad}${BASH_REMATCH[3]}" )
done
# If there are any files to rename, ask to confirm the operation.
# And rename if confirmed.
if [[ -n "${oldfile[*]}" ]]; then
echo
echo -e "${BCYAN}Rename the following files?${RESET}"
echo
for i in "${!oldfile[@]}" ; do
echo -e "${oldfile[i]/#$PWD/.}\t-->\t${newfile[i]/#$PWD/.}"
done
echo
read -p "(y/n): "
echo
case "$REPLY" in
y|Y*) for i in "${!oldfile[@]}" ; do
mv -n "${oldfile[i]}" "${newfile[i]}"
done
echo
;;
*) echo -e "${BCYAN}Aborting.${RESET}"
echo
exit 1
;;
esac
# Otherwise just exit.
else
echo
echo -e "${BCYAN}No files to rename.${RESET}" >&2
echo -e "${BCYAN}Exiting.${RESET}" >&2
echo
exit 1
fi
exit 0
