Can't use $myvar_.* to mv files starting with $myvar_

Question

week=$(date +%W)

I'm trying to move files beginning with $week to another folder using mv.

So I have a file named:

25_myfile.zip

And the number at the beginning is a number of a week. So I want to move it using mv from the directory it's currently in to /mydir/week25/:

mv /mydir/$week\_.* /mydir/week$week;

But I get a stat error.

Answer 1

The problem

When you say

mv /mydir/$week\_.* /mydir/week$week;
#                ^^

You are using the syntax $var\_.* (or ${var}_.* if you don't want to have to escape the underscore) you are trying to use globbing, but failing because you use a regular expression syntax.

The solution

Use globbing as described in Bash Reference Manual → 3.5.8 Filename Expansion. That is

After word splitting, unless the -f option has been set (see The Set Builtin), Bash scans each word for the characters ‘*’, ‘?’, and ‘[’. If one of these characters appears, then the word is regarded as a pattern, and replaced with an alphabetically sorted list of filenames matching the pattern (see Pattern Matching).

mv /mydir/$week\_* /mydir/week$week;
#                ^

or, using ${ } to define the scope of the name of the variable:

mv /mydir/${week}_* /mydir/week$week;
#          ^    ^ ^

Another approach

You just need an expression like:

for file in <matching condition>; do
     mv "$file" /another/dir
done

In this case:

for file in ${week}_*; do
   mv "$file" /mydir/week"${week}"/
done

Because ${week}_* will expand to those filenames starting with $week plus _.

See an example:

$ touch 23_a
$ touch 23_b
$ touch 23_c
$ touch 24_c
$ d=23
$ echo ${d}*
23_a 23_b 23_c
$ for f in ${d}*; do echo "$f --"; done
23_a --
23_b --
23_c --