On 03/14/2014 04:05 PM, Reuben Thomas wrote: >>> Why doesn't bash just remove the hashed path and do a normal PATH >> search? I >>> have to remove it manually. >> >> Look at the description of the `checkhash' option to `shopt'. It does what >> you want; it's just not the default. >> > > Thanks. Why is it not the default? Shouldn't an optimisation (hashing PATH > lookup) be transparent to the user by default? >
For that matter, POSIX requires the 'checkhash' behavior: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#set http://pubs.opengroup.org/onlinepubs/9699919799/utilities/hash.html http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_09_01_01 In particular: "Once a utility has been searched for and found (either as a result of this specific search or as part of an unspecified shell start-up activity), an implementation may remember its location and need not search for the utility again unless the PATH variable has been the subject of an assignment. If the remembered location fails for a subsequent invocation, the shell shall repeat the search to find the new location for the utility, if any." So the three ways to reset a hash without resorting to the non-portable shopt are 'hash -r', 'PATH=$PATH', or causing lookup to fail - but bash is not honoring the third way by default (I didn't test if bash in 'set -o posix' behaves differently). -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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