查找命令可从命令行运行，但不能在脚本中运行

Question

I am working on a process that needs to run every night and will tar.gz a large list of files (too large to do with the tar command). To workaround this, I can create a list of files I want tar to archive and pass it in. I usually do this manually, but I'd like to automate it using a crontab.

The OS in this case is RedHat Enterprise 6.3 (Santiago).

I have the following bash shell script:

#!/bin/bash

now=$(date +"%Y%m%d")

TARGET_DIR=/usr/share/data

FILE_LIST=/home/user/txt-files/data-as-of-$now.txt

if [ -e $FILE_LIST ];
then
    rm -rf $FILE_LIST
fi

CMD="find $TARGET_DIR -regextype posix-extended -regex \".*/$now.*\" -fprint $FILE_LIST"

echo $CMD

findCmd=`$CMD`

if [ $? -ne 0 ];
then
    echo "command failed; $findCmd"
fi

The script runs fine but doesn't write anything to the file specified in the -fprint argument. If I take the command that is echo'd out and copy and paste it to cli, it works like I expect and my file has the list of files I want.

find /usr/share/data -regextype posix-extended -regex ".*/20140624.*" -fprint /home/user/txt-files/data-as-of-20140624.txt

I am guessing that there is something funky about the regex that gets interpreted incorrectly when running as a script but not as a command from the CLI. I've read in other threads about the need to enclose the asterisk in quotes, and I've tried the single tick and double tick, neither seem to work. I've also tried the back tick way of executing the command and the $() way, both yield the same result.

If I were getting any errors or messages this would be less perplexing. If anyone could look and see if I am doing something blatantly wrong, I'd appreciate the pointer!

If I run the command with bash -x, I get this output:

[user@data-provider bin]$ bash -x tgz2.sh
++ date +%Y%m%d
+ now=20140624
+ TARGET_DIR=/usr/share/data
+ FILE_LIST=/home/user/txt-files/data-as-of-20140624.txt
+ '[' -e /home/user/txt-files/data-as-of-20140624.txt ']'
+ rm -rf /home/user/txt-files/data-as-of-20140624.txt
+ CMD='find /usr/share/data -regextype posix-extended -regex '\''.*/20140624.*'\'' -fprint /home/user/txt-files/data-as-of-20140624.txt'
+ echo find /usr/share/data -regextype posix-extended -regex ''\''.*/20140624.*'\''' -fprint /home/user/txt-files/data-as-of-20140624.txt
find /usr/share/data -regextype posix-extended -regex '.*/20140624.*' -fprint /home/user/txt-files/data-as-of-20140624.txt
++ find /usr/share/data -regextype posix-extended -regex ''\''.*/20140624.*'\''' -fprint /home/user/txt-files/data-as-of-20140624.txt
+ findCmd=
+ '[' 0 -ne 0 ']'

Answer 1

Switching to just the below syntax in the script, without any variable assignment, fixed the issue.

find $TARGET_DIR -regextype posix-extended -regex ".*/$now.*" -fprint $FILE_LIST

The problem with the original syntax, which I tested with

cmd="find -regex '.*/test.*' -fprint out.txt
$cmd

is that it gets run as

find -regex ''\''.*/test.*'\''' -fprint out.txt

but not entirely sure why variable substitution adds the erroneous single quotes.