检查文件扩展名 BASH

Question

I'm trying to compare 2 files that have the same name and the same contents but I only want to keep one of them. Lets say I have the following

/root/dir1/file1.doc
/root/dir1/file1.pdf 

I only want to keep the .doc file what would be the best way to go about this?

Answer 1

From the dash manpage (and I believe all bash , ksh , and zsh "inherit" these features):

${parameter%word} Remove Smallest Suffix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the smallest portion of the suffix matched by the pattern deleted.

${parameter%%word} Remove Largest Suffix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest portion of the suffix matched by the pattern deleted.

${parameter#word} Remove Smallest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the smallest portion of the prefix matched by the pattern deleted.

${parameter##word} Remove Largest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest portion of the prefix matched by the pattern

In practice:

shortSuff(){ printf '%s\n' "${1#*.}"; } 
#^applies the string op to the $1 positional parameter
#`printf '%s\n'` is like `echo` but doesn't break on e.g., hyphen-prefix arguments

file=/root/dir1/file1.doc
[ shortSuff "$file" = doc ] && echo "Yes, the short suffix is doc"

Answer 2

You can write a short script to do this for you:

#!/bin/bash
EXT="${1}"
if -z "${EXT}"; then EXT=".doc"; fi
TD="$(mktemp -d)"
mv ./*"${EXT}" "${TD}"
rm ./*
mv "${TD}"/* .
rmdir "${TD}"

Assuming your script is called keep_copy.sh , you would call it as follows: keep_copy.sh .doc .