Questions[ksh](server)

I manage an AIX box at work using PuTTY. I'm using ksh in vi-mode. When I press the Delete key (not backspace) the case of following characters is toggled instead of the character under the cursor being deleted. I'm not necessarily looking to change the behavior, as this is a very important server and I just don't want to make unnecessary changes, but I would like to understand why it's happening.

Steps to reproduce.

1. Type some text:

   root:common> ls -al

2. Move the cursor over the dash. ([esc] hhh)
3. Press the Delete Key. ([del])
4. Strange things happen:

   root:common> ls -AL

Expected behavior: The character under the cursor is deleted.

Actual behavior: Following characters have their case toggled.

I've got a bizarre seeming shell issue, with a command in the $PATH that the shell (ksh, running on Linux) appears to cowardly refuse to invoke. Without fully qualifying the command, I get:

#  mycommand
/bin/ksh: mycommand: not found [No such file or directory]

but the file can be found by which:

#  which mycommand
/home/me/mydir/admbin/mycommand

I also explicitly see that directory in $PATH:

#  echo $PATH | tr : '\n' | grep adm
/home/me/mydir/admbin

The exe at that location seems normal:

#  file /home/me/mydir/admbin/mycommand
/home/me/mydir/admbin/mycommand: setuid setgid ELF 64-bit LSB executable, x86-64, version 1 (SYSV), for GNU/Linux 2.6.4, dynamically linked (uses shared libs), not stripped

# ls -l mycommand  
-r-sr-s--- 1 me mygroup 97892 2012-04-11 18:01 mycommand

and if I run it explicitly using a fully qualified path:

#  /home/me/mydir/admbin/mycommand

I see the expected output. Something is definitely confusing the shell here, but I'm at a loss what it could be?

EDIT: finding what looked like a similar question: Binary won't execute when run with a path. Eg >./program won't work but >program works fine

I also tested for more than one such command in my $PATH, but find only one:

# for i in `echo $PATH | tr : '\n'` ; do test -e $i/mycommand && echo $i/mycommand ; done
/home/me/mydir/admbin/mycommand

EDIT2:

As of this morning, the problem has vanished, and I'm now able to execute the executable.

That could be thought of as validating the suggestion to logout and login, but I'd done that last night without success. That logout/login should have also done the equivalent of running the 'hash -r' command that was suggested (which fwiw also appears to be a ksh builtin, and not just a bash builtin).

In response to some of the answers:

• This is an executable not a script (see the ELF reference in the file command output).

• I don't think that a strace would have helped. That ends up forcing the command to execute fully qualified. I suppose that I could have done a strace attach on the current shell, but since I can no longer repro there's no point of trying that.

• there were no semicolons in the $PATH. Since I can no longer repro, I won't clutter up this question with the full $PATH.

• trying another shell (i.e. bash) would have been something I'd also have tried, as was suggested. With the problem gone, I now won't know if that would have helped.

It was also suggested to me was checking the directory permissions. Doing so, for each of the directories up to this one I see:

# ls -ld $HOME $HOME/mydir $HOME/mydir/admbin
drwxr-xr-x 10 me root    4096 2012-04-12 12:20 /home/me
drwxrwsr-t 22 me mygroup 4096 2012-04-12 12:04 /home/me/mydir
drwxr-sr-x  2 me mygroup 4096 2012-04-12 12:04 /home/me/mydir/admbin

The $HOME directory ownership is messed up (shouldn't be root group). That could cause other issues, but I don't see how it would have caused this one.

The target of the following simple expect script is to get the hostname name on the remote machine

Sometimes expect script fail to perform ssh to $IP_ADDRESS ( because remote machine not active , etc )

so in this case the expect script will break after 10 second (timeout 10) , this is OK but......

There are two options

1. Expect script perform ssh successfully , and performed the command hostname on the remote machine
2. Expect script break because timeout was 10 seconds

On both cases expect will exit

• in case of ssh successfully expect will break after 0.5-1 second but in case of bad ssh then it will break after 10 seconds

but I don’t know if expect script perform ssh successfully or not?

is it possible to identify timeout process ? or to verify that expect ended because timeout?

Remark my Linux machine version - red-hat 5.1

Expect script

 [TestLinux]# get_host_name_on_remote_machine=`cat << EOF
  > set timeout 10
  > spawn  ssh   $IP_ADDRESS
  >            expect {
  >                      ")?"   { send "yes\r"  ; exp_continue  }
  > 
  >                      word:  {send $PASS\r}
  >                   }
  > expect >  {send "hostname\r"}
  > expect >    {send exit\r}
  > expect eof
  > EOF`

Example in case we not have connection to the remote host

 [TestLinux]# expect -c  "$get_host_name_on_remote_machine"
 spawn ssh 10.17.180.23
 [TestLinux]# echo $?
 0

in my linux machine red-hat 5.1 - in ppp file - I have only the signature.pl string !!!

• remark - third application write the signature.pl string in to ppp file

I set ppp file in $a param And compare $a with signature.pl

But as all see here this not equal - why ? or if I have empty space? How to solve this?

    # more /var/tmp/ppp
    signature.pl
    # a=`cat /var/tmp/ppp`
    # echo $a
    signature.pl
    # [[ $a = signature.pl ]] && echo equal

or

    # [[ $a == signature.pl ]] && echo equal

diff example that works ! - from ksh shell (LINUX RED-HAT 5.1)

[u@h w]# echo signature.sh > file
[u@h w]# cat file
signature.sh
[u@h w]# a=`cat file`  
[u@h w]# echo $a
signature.sh
[u@h w]# [[ $a = signature.sh ]] && echo eq

 its print "eq"

From the looks of things, fixing ksh to make history alteration impossible is fairly easy. I've seen all the recommendations to make HIST* environment variables read-only, and the use of chattr to make the history file append-only (with chattr +a .sh_history).

Bash, however, has two things which seem to make it impossible to prevent history alteration: the history command (with history -c and history -d) and the separation of the history file from the actual run-time history (kept in memory). I also read here on serverfault that if you kill the current shell, then history won't be written out.

Is there any way to prevent history alteration for Bash? I want to be able to save all user commands without the user being able to remove anything from the history whatsoever.

Any further tips on Korn shell are also welcome. (I know about ksh-93 auditing... don't know if we can use it.)