用* shell bash读取文件名

Question

I'am new in Linux and I want to write a bash script that can read in a file name of a directory that starts with LED + some numbers.(Ex.: LED5.5.002)

In that directory there is only one file that will starts with LED. The problem is that this file will every time be updated, so the next time it will be for example LED6.5.012 and counting.

I searched and tried a little bit and came to this solution:

export fspec=/home/led/LED*
LedV=`basename $fspec`
echo $LedV

If I give in those commands one by one in my terminal it works fine, LedV= LED5.5.002 but if i run it in a bash scripts it gives the result: LedV = LED*

I search after another solution:

a=/home/led/LED* LedV=$(basename $a) echo $LedV

but here again the same, if i give it in one by one it's ok but in a script: LedV = LED*.

It's probably something small but because of my lack of knowledge over Linux I cannot find it. So can someone tell what is wrong?

Thanks! Jan

Answer 1

Shell expansions don't happen on scalar assignments, so in

varname=foo*

the expansion of "$varname" will literally be "foo*" . It's more confusing when you consider that echo $varname (or in your case basename $varname ; either way without the double quotes) will cause the expansion itself to be treated as a glob, so you may well think the variable contains all those filenames.

Array expansions are another story. You might just want

fspec=( /path/LED* )
echo "${fspec[0]##*/}" # A parameter expansion to strip off the dirname

That will work fine for bash. Since POSIX sh doesn't have arrays like this, I like to give an alternative approach:

for fspec in /path/LED*; do
    break
done
echo "${fspec##*/}"

Answer 2

pwd
/usr/local/src

ls -1 /usr/local/src/mysql*
    /usr/local/src/mysql-cluster-gpl-7.3.4-linux-glibc2.5-x86_64.tar.gz
    /usr/local/src/mysql-dump_test_all_dbs.sql

if you only have 1 file, you will only get 1 result

MyFile=`ls -1 /home/led/LED*`