How to invoke bash run commands inside the new shell and then give control back to user

Question

This must either be really simple or really complex  but I couldn t find anything about it    I am trying to open a new bash instance  then run a few commands inside it  and give the control back to the user inside that same instance   I tried     bash -lic  some command    but this executes some command inside the new instance  then closes it  I want it to stay open   One more detail which might affect answers  if I can get this to work I will use it in my  bashrc as alias es   so bonus points for an alias implementation

User · Accepted Answer

bash --rcfile  lt  echo       bashrc  some command     dispenses the creation of temporary files  Question on other sites    https   serverfault com questions 368054 run-an-interactive-bash-subshell-with-initial-commands-without-returning-to-the https   unix stackexchange com questions 123103 how-to-keep-bash-running-after-command-execution

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bash --init-file  lt  echo  some command     bash --rcfile  lt  echo  some command     In case you can t or don t want to use process substitution     cat script some command   bash --init-file script   Another way     bash -c  some command  exec bash    sh -c  some command  exec sh    sh-only way  dash  busybox      ENV script sh

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This is a late answer  but I had the exact same problem and Google sent me to this page  so for completeness here is how I got around the problem   As far as I can tell  bash does not have an option to do what the original poster wanted to do  The -c option will always return after the commands have been executed    Broken solution  The simplest and obvious attempt around this is   bash -c  XXXX   bash    This partly works  albeit with an extra sub-shell layer   However  the problem is that while a sub-shell will inherit the exported environment variables  aliases and functions are not inherited  So this might work for some things but isn t a general solution   Better  The way around this is to dynamically create a startup file and call bash with this new initialization file  making sure that your new init file calls your regular    bashrc if necessary     Create a temporary file TMPFILE   mktemp     Add stuff to the temporary file echo  source    bashrc   gt   TMPFILE echo   lt other commands gt    gt  gt   TMPFILE echo  rm -f  TMPFILE   gt  gt   TMPFILE    Start the new bash shell  bash --rcfile  TMPFILE   The nice thing is that the temporary init file will delete itself as soon as it is used  reducing the risk that it is not cleaned up correctly   Note  I m not sure if  etc bashrc is usually called as part of a normal non-login shell  If so you might want to source  etc bashrc as well as your    bashrc

User · Answer

Append to    bashrc a section like this   if     subshell     true    then       commands to execute only on a subshell     date fi alias sub  subshell true bash    Then you can start the subshell with sub

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You can pass --rcfile to Bash to cause it to read a file of your choice   This file will be read instead of your  bashrc    If that s a problem  source    bashrc from the other script    Edit  So a function to start a new shell with the stuff from    more sh would look something like   more     bash --rcfile    more sh           and in  more sh you would have the commands you want to execute when the shell starts    I suppose it would be elegant to avoid a separate startup file -- you cannot use standard input because then the shell will not be interactive  but you could create a startup file from a here document in a temporary location  then read it

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With accordance with the answer by daveraja  here is a bash script which will solve the purpose   Consider a situation if you are using C-shell and you want to execute a command without leaving the C-shell context window as follows   Command to be executed  Search exact word  Testing  in current directory recursively only in   h    c files  grep -nrs --color -w --include     h c   Testing      Solution 1  Enter into bash from C-shell and execute the command  bash grep -nrs --color -w --include     h c   Testing    exit   Solution 2  Write the intended command into a text file and execute it using bash  echo  grep -nrs --color -w --include     h c   Testing      gt  tmp file txt bash tmp file txt   Solution 3  Run command on the same line using bash  bash -c  grep -nrs --color -w --include     h c   Testing       Solution 4  Create a sciprt  one-time  and use it for all future commands  alias ebash    execute command on bash sh  ebash grep -nrs --color -w --include     h c   Testing      The script is as follows      bin bash                                                                               References    https   stackoverflow com a 13343457 5409274   https   stackoverflow com a 26733366 5409274   https   stackoverflow com a 2853811 5409274   https   stackoverflow com a 2853811 5409274   https   www linuxquestions org questions other- 2Anix-55 how-can-i-run-a-command-on-another-shell-without-changing-the-current-shell-794580    https   www tldp org LDP abs html internalvariables html   https   stackoverflow com a 4277753 5409274                                                                                Enable following line to see the script commands   getting printing along with their execution  This will help for debugging   set -o verbose  E BADARGS 85  if     -n   1    then   echo  Usage   basename  0  grep -nrs --color -w --include      h c    Testing      echo  Usage   basename  0  find   -name     txt      exit  E BADARGS fi      Create a temporary file TMPFILE   mktemp     Add stuff to the temporary file  echo  echo Hello World       gt  gt   TMPFILE   initialize the variable that will contain the whole argument string argList     iterate on each argument for arg in      do    if an argument contains a white space  enclose it in double quotes and append to the list    otherwise simply append the argument to the list   if echo  arg   grep -q      then    argList   argList    arg      else    argList   argList  arg    fi done   remove a possible trailing space at the beginning of the list argList   echo  argList   sed  s            Echoing the command to be executed to tmp file echo   argList   gt  gt   TMPFILE    Note  This should be your last command   Important last command which deletes the tmp file last command  rm -f  TMPFILE  echo   last command   gt  gt   TMPFILE   echo  ---------------------------------------------   echo  TMPFILE is  TMPFILE as follows   cat  TMPFILE  echo  ---------------------------------------------   check for last line   tail -n 1  TMPFILE   grep -o   last command    echo  check for last line   if tail -n 1  TMPFILE   grep -o   last command  if     check for last line       last command    then    echo  Okay       bash  TMPFILE   exit 0 else   echo  Something is wrong    echo  Last command in your tmp file should be removing itself    echo  Aborting the process    exit 1 fi

User · Answer

The accepted answer is really helpful   Just to add that process substitution  i e    lt  COMMAND   is not supported in some shells  e g   dash    In my case  I was trying to create a custom action  basically a one-line shell script  in Thunar file manager to start a shell and activate the selected Python virtual environment   My first attempt was   urxvt -e bash --rcfile  lt  echo     HOME  bashrc     f bin activate      where  f is the path to the virtual environment handled by Thunar  I got an error  by running Thunar from command line     bin sh  1  Syntax error      unexpected   Then I realized that my sh  essentially dash  does not support process substitution   My solution was to invoke bash at the top level to interpret the process substitution  at the expense of an extra level of shell   bash -c  urxvt -e bash --rcfile  lt  echo  source  HOME  bashrc  source  f bin activate         Alternatively  I tried to use here-document for dash but with no success   Something like   echo -e    lt  lt EOF n   HOME  bashrc     f bin activate  nEOF n    xargs -0 urxvt -e bash --rcfile   P S   I do not have enough reputation to post comments  moderators please feel free to move it to comments or remove it if not helpful with this question

User · Answer

You can get the functionality you want by sourcing the script instead of running it   eg     cat script cmd1 cmd2     script   at this point cmd1 and cmd2 have been run inside this shell

User · Answer

Here is yet another  working  variant  This opens a new gnome terminal  then in the new terminal it runs bash  The user s rc file is read first  then a command ls -la is sent for execution to the new shell before it turns interactive  The last echo adds an extra newline that is needed to finish execution  gnome-terminal -- bash -c  bash --rcfile  lt   cat    bashrc  echo ls -la   echo    I also find it useful sometimes to decorate the terminal  e g  with colorfor better orientation  gnome-terminal --profile green -- bash -c  bash --rcfile  lt   cat    bashrc  echo ls -la   echo

User · Answer

Executing commands in a background shell  Just add  amp  to the end of the command  e g   bash -c some command  amp  amp  another command  amp

[shell] How to invoke bash, run commands inside the new shell, and then give control back to user?

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