Linux command executed from a different path than whereis

bashlinux

I installed paris-traceroute and I don't remember what I did to replace the ping packaged with Ubuntu Trusty with paris-ping, which requires root to run. Now I want to get rid of it.

$ ping --version
version 1.0

$ whereis ping
ping: /bin/ping /usr/share/man/man8/ping.8.gz

$ ping
-bash: /usr/local/bin/ping: No such file or directory

paris-ping was at /usr/local/bin/ping. I deleted that file but now the ping command still does not run from /bin/ping. What I am missing here?

Best Answer

It's because you haven't started a new shell since you deleted the binary.

Use that command to reload the locations of the binaries:

hash -r

Or just restart the shell.

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Check this link if you're facing the same problem.

Default configuration file depends on which shell you're using. Back to my question, I forgot to check ~/.zprofile("waterwood" is set in this file).

Linux – cron apparently requires a newline character on its own line at the end of the file

Is this a bug?

No. I created a file with no newline character at the end. Nevertheless Vim (after :set list) shows $ at the end. It looks like your premise is false, your file is missing a final newline, cron works as intended.

Notes:

POSIX requires a trailing newline character to consider any line to be complete.

3.195 Incomplete Line
A sequence of one or more non-<newline> characters at the end of the file.

[…]

3.206 Line
A sequence of zero or more non-<newline> characters plus a terminating <newline> character.

So the behavior of cron is not just an arbitrary quirk (although the tool might not be that restrictive). For more insight see Why should text files end with a newline?
Vim with default settings will fix the missing newline while saving, unless you tell it not to.
To tell whether there is a newline character at the end or not, make a hexdump of the file, e.g. hexdump the_file or xxd the_file. In case of your crontab this may be hard. In my Debian the crontab is /var/spool/cron/crontabs/kamil, but since I have no access to /var/spool/cron/crontabs/ as a normal user, I cannot just xxd the file. To overcome this I can use the following trick:
```
EDITOR=xxd crontab -e
```
There is a newline at the end iff the last byte reports as 0a.

Best Answer

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Linux – cron apparently requires a newline character on its own line at the end of the file

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