Hi all,
These are just a couple of thoughts I've had that we've discussed a
little in IRC recently. They aren't exactly earth-shattering, but I
think they might still be of use to someone.
Shell aliases which give default arguments, like alias ls='ls -1', are
useful but must be invoked from the shell, which means they aren't
'first class citizens' as programs in Unix. The solution, then, is to
have small scripts in ~/bin which wrap the program, like ~/bin/ls:
#!/bin/sh
exec /bin/ls -1 "$@"
The problem with this is that now we've circumvented $PATH by saying
'exec /bin/ls', an absolute path, rather than simply 'ls'. But if we
did say 'exec ls' then it would infinite loop, with ~/bin/ls executing
~/bin/ls... Our solution was 'next', a shell script which works out
the executable in $PATH to execute *after* the current one. So instead
you would say:
#!/bin/sh
exec next "$0" -1 "$@"
This has proven quite convenient. The script is as follows:
#!/bin/sh
dir=${1%/*}
bin=${1##*/}
shift
unset flag
set -f
IFS=:
for d in $PATH; do
if [ "$d" = "$dir" ]; then
flag=1
elif [ -n "$flag" ] && [ -x "$d/$bin" ]; then
exec "$d/$bin" "$@"
fi
done
printf "%s: no '%s' found beyond '%s' in \$PATH\n" "${0##*/}"
"$bin" "$dir" >&2
exit 127
Thanks,
cls
