Why do I get different results for the history command for the same user after I reconnect a disconnected SSH session?I connect to a server using putty (SSH), say as rootMy network gets disconnectedI reconnect my putty sessionWhen I hit my up arrow key to re-run the last used command, it shows a different commandI am guessing this is due to getting reconnected to a different pts. Am I right?
Different history command output after reconnecting via SSH
shell;ssh;command history
This is because history of your commands from current session are flushed on disk during logging off. And if you has been disconnected, when you connect again you will get last flushed history.You can also manually flush history to disk by running:history -aRefer to man history:   history [n]   history -c   history -d offset   history -anrw [filename]   history -p arg [arg ...]   history -s arg [arg ...]          With no options, display the command history list with line numbers.  Lines listed with a * have been  modified.          An  argument  of n lists only the last n lines.  If the shell variable HISTTIMEFORMAT is set and not null, it is          used as a format string for strftime(3) to display the time stamp associated with each displayed history  entry.          No intervening blank is printed between the formatted time stamp and the history line.  If filename is supplied,          it is used as the name of the history file; if not, the value of HISTFILE is used.  Options, if  supplied,  have          the following meanings:          -c     Clear the history list by deleting all the entries.          -d offset                 Delete the history entry at position offset.          -a     Append  the new history lines (history lines entered since the beginning of the current bash session)                 to the history file.          -n     Read the history lines not already read from the history file into the current history list.   These  are                 lines appended to the history file since the beginning of the current bash session.          -r     Read the contents of the history file and use them as the current history.          -w     Write the current history to the history file, overwriting the history files contents.          -p     Perform  history  substitution on the following args and display the result on the standard output.  Does                 not store the results in the history list.  Each arg must be quoted to disable normal history  expansion.          -s     Store  the  args  in the history list as a single entry.  The last command in the history list is removed                 before the args are added.          If the HISTTIMEFORMAT variable is set, the time stamp information associated with each history entry is  written          to  the history file, marked with the history comment character.  When the history file is read, lines beginning          with the history comment character followed immediately by a digit are interpreted as timestamps for the  previ-          ous  history line.  The return value is 0 unless an invalid option is encountered, an error occurs while reading          or writing the history file, an invalid offset is supplied as an argument to -d, or the history  expansion  sup-          plied as an argument to -p fails.