Did you test it with filenames containing IFS characters? Assuming a default IFS value, your option handling, sed invocations, and cat statement will all barf if a filename contains whitespace.
Code:
for opt in $*
should be
Code:
for opt in "$@"
All instances of $3 need to be double-quoted.
Alister
Okay, I'll change that then.
EDIT: I fixed the script. It now looks like this:
Code:
#!/bin/bash
# deletes lines of a certain range length from a file
# Writing the result to the file is optional.
write="no";
for opt in "$@"
do
case "$opt" in
-w ) write="yes";
shift;;
-* ) shift;;
* );;
esac
done
least=$1;
great=$2;
shift;
shift;
filname="$*";
if [ $write == "yes" ]
then
sed -e "/^.\{$least,$great\}$/d" "$filname" > tempfile.txt;
cat tempfile.txt > "$filname";
rm tempfile.txt;
else
sed -e "/^.\{$least,$great\}$/d" "$filname";
fi
unset write
All I did was put quotation marks around the filename. I was also able to fix another script that I wrote a while back which was having the same problem.
Actually I've found I don't have to use "$@". It works whether I use that or $*. The quotation marks were the only problem.
Actually I've found I don't have to use "$@". It works whether I use that or $*. The quotation marks were the only problem.
If you aren't using "$@" in that situation, then your script has a bug. There is no doubt about it.
Using $@ without quotes or $* with or without quotes will not expand to each individual command line argument (positional parameter in sh man page lingo). If unquoted, $@ and $* behave identically; they will expand to a list of words and then (this is the problem) each word (a positional parameter at this point) will be split according to the current setting of IFS (after splitting, the words may no longer correspond to the positional parameters). If you quote $*, you end up with one word containing all your positional parameters, regardless of how many parameters there are.
In that for loop, "$@" is the only correct option. If you don't believe me, try $* or $@ with a file name containing a space (assuming default IFS value) followed by one of your program's valid options, such as "infile -w". Even if the -w option isn't passed, such a filename will trigger it because "infile -w" will be split into two words, "infile" and "-w". That would be a bug. I realize that's a contrived and unlikely filename, but the point is that the option handling is behaving erroneously.
If you don't see it, read the sh man page carefully, with particular emphasis on the special parameters $@ and $*, quoting, and word splitting.
Here's some exemplary code:
Code:
$ cat o.sh
#!/bin/bash
printf '==================================================\n'
printf '$@: INCORRECT: Word splitting after $@ expansion yields 3 words.\n'
for opt in $*
do
case "$opt" in
* )echo "$opt";;
esac
done
printf '==================================================\n'
printf '$*: INCORRECT: Word splitting after $* expansion yields 3 words.\n'
for opt in $*
do
case "$opt" in
* )echo "$opt";;
esac
done
printf '==================================================\n'
printf '"$*": INCORRECT: Always expands to one word, regarless of $# positional parameter count.\n'
for opt in "$*"
do
case "$opt" in
* )echo "$opt";;
esac
done
printf '==================================================\n'
printf '"$@": CORRECT: Expands to one word per positional parameter without subsequent word splitting.\n'
for opt in "$@"
do
case "$opt" in
* )echo "$opt";;
esac
done
# Let's call the script with two positional parameters.
# Only "$@" will expand to the two correct words, while the others result in 1 or 3.
$ ./o.sh -v 'input -w'
==================================================
$@: INCORRECT: Word splitting after $@ expansion yields 3 words.
-v
input
-w
==================================================
$*: INCORRECT: Word splitting after $* expansion yields 3 words.
-v
input
-w
==================================================
"$*": INCORRECT: Always expands to one word, regarless of $# positional parameter count.
-v input -w
==================================================
"$@": CORRECT: Expands to one word per positional parameter without subsequent word splitting.
-v
input -w
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textline2
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TESTING
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I have a textfile containing text similar to the following pattern:
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