I want to set up an array using command line parameters. The user can either provide a list of files or the script locates them somehow. So I have:
#!/bin/bash
echo given n=$#, v=$*
[ $# -gt 0 ] && files=(${*}) || files=(/tmp/cap*)
echo num files = ${#files[@]}
echo files = ${files[@]}
But when I run it with a file list, I get into trouble:
$ /tmp/foo a b '4 4 4' c d
given n=5, v=a b 4 4 4 c d
num files = 7
files = a b 4 4 4 c d
How do I effectively get tmp=($*)?
Replace
files=(${*})
with
files=("$@")
What's the difference between $* and $@? The bash man page says:
$*Expands to the positional parameters, starting from one. When the expansion is not within double quotes, each positional parameter expands to a separate word. In contexts where it is performed, those words are subject to further word splitting and pathname expansion. When the expansion occurs within double quotes, it expands to a single word with the value of each parameter separated by the first character of the IFS special variable. That is,
"$*"is equivalent to"$1c$2c...", where c is the first character of the value of the IFS variable. If IFS is unset, the parameters are separated by spaces. If IFS is null, the parameters are joined without intervening separators.
$@Expands to the positional parameters, starting from one. When the expansion occurs within double quotes, each parameter expands to a separate word. That is,
"$@"is equivalent to"$1" "$2"... If the double-quoted expansion occurs within a word, the expansion of the first parameter is joined with the beginning part of the original word, and the expansion of the last parameter is joined with the last part of the original word. When there are no positional parameters,"$@"and$@expand to nothing (i.e., they are removed).
You'll almost always want to use "$@" over $@, "$*", or $*.
c_star ()
{
printf 'argc: %s\n' "$#";
printf Unquoted\\n
printf 'argv: %s\n' $*
printf Quoted\\n
printf 'argv: %s\n' "$*"
}
c_at ()
{
printf 'argc: %s\n' "$#";
printf Unquoted\\n
printf 'argv: %s\n' $@
printf Quoted\\n
printf 'argv: %s\n' "$@"
}
$ c_star a b '4 4 4' c d
argc: 5
Unquoted
argv: a
argv: b
argv: 4
argv: 4
argv: 4
argv: c
argv: d
Quoted
argv: a b 4 4 4 c d
$ c_at a b '4 4 4' c d
argc: 5
Unquoted
argv: a
argv: b
argv: 4
argv: 4
argv: 4
argv: c
argv: d
Quoted
argv: a
argv: b
argv: 4 4 4
argv: c
argv: d
So, given the above, and that you want each argument as its own value in the array you want the expansion of "$@" so use files=("$@").
$*use$@.