/usr/sbin/add-shell is in debianutils 4.4.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 | #!/bin/sh -e
if test $# -eq 0
then
echo usage: $0 shellname [shellname ...]
exit 1
fi
file=/etc/shells
# I want this to be GUARANTEED to be on the same filesystem as $file
tmpfile=${file}.tmp
set -o noclobber
trap "rm -f $tmpfile" EXIT
if ! awk '{print}' $file > $tmpfile
then
cat 1>&2 <<EOF
Either another instance of $0 is running, or it was previously interrupted.
Please examine ${tmpfile} to see if it should be moved onto ${file}.
EOF
exit 1
fi
for i
do
if ! grep -q "^${i}$" $tmpfile
then
echo $i >> $tmpfile
fi
done
chmod --reference=$file $tmpfile
chown --reference=$file $tmpfile
mv $tmpfile $file
trap "" EXIT
exit 0
|