On 18/08/2014 12:29, Stroller wrote:
On Mon, 18 August 2014, at 10:42 am, wraeth <wra...@wraeth.id.au> wrote:
On Mon, 2014-08-18 at 18:54 +1000, Adam Carter wrote:
But this matches if grep fails both times as well as when it matches both
time. Any ideas?
If you don't mind using a quick loop, you could use something like:
n=0
for f in file1.txt file2.txt file3.txt file4.txt; do
grep 'string' ${f} >> /dev/null && n=$[n+1]
done
if [[ $n == 4 ]]; then
do_something
fi
I've solved similar problems the same way myself, but I hope you'll forgive me
for offering unsolicited critique on a small detail.
In the above 4 is a constant, and thus it's independent of the number of files
being tested.
I propose addressing this with an array of the filenames.
Thus additional files can be added for testing, without manual adjustment of
the expected total.
files=("file1.txt" "file2.txt" "file3.txt" "file4.txt")
n=0
for f in ${files[@]}; do
grep 'string' ${f} >> /dev/null && n=$[n+1]
I would write `grep -q -m1 -F 'string' ...` here. In particular, -m1
will short-circuit after finding one match.
done
if [[ $n == ${#files[@]} ]]; then
do_something
fi
Bash array syntax is a bit arcane, but at least these very useful data
structures are available.
Here's a slightly different take. It avoids multiple grep invocations,
which could be a good thing in the case of a lengthy file list.
files=(file1.txt file2.txt file3.txt file4.txt)
string="matchme" # Using -F below as it's a string, not a regex
count=0
while read -r matches; do
(( count += matches ))
done < <(grep -hcm1 -F "$string" ${files[*]})
if (( count == ${#files[@]} )); then
do_something
fi
--Kerin
