Delete all SYSTEM V shared memory and semaphores on UNIX-like systems

Question

How can I delete all not used semaphores and shared memory with a single command on a UNIX-like system  e g   Ubuntu

User · Answer

Check if there is anything to delete with :

ipcs -a | grep `whoami`

On linux delete them all via :

ipcs | nawk -v u=`whoami` '/Shared/,/^$/{ if($6==0&&$3==u) print "ipcrm shm",$2,";"}/Semaphore/,/^$/{ if($3==u) print "ipcrm sem",$2,";"}' | /bin/sh

For sun it would be :

ipcs -a | nawk -v u=`whoami` '$5==u &&(($1=="m" && $9==0)||($1=="s")){print "ipcrm -"$1,$2,";"}' | /bin/sh

courtsesy of di.uoa.gr

Check again if all is ok

For deleting your sems/shared mem - supposing you are a user in a workstation with no admin rights

User · Answer

This is how I do it in FreeBSD       usr local bin bash for i in   ipcs -a   grep   s    awk    print  2      do         echo  ipcrm -s  i          ipcrm -s  i done

User · Answer

In addition to bvamos s answer  according to the documentation the use of sem is deprecated       NAME ipcrm - remove a message queue  semaphore set or shared memory id   SYNOPSIS ipcrm   -M key   -m id   -Q key   -q id   -S key   -s id         deprecated usage      ipcrm   shm   msg   sem   id       remove shared memory  us ipcrm -m to remove a shared memory segment by the id     bin bash  set IPCS M   ipcs -m   egrep  0x 0-9a-f    0-9      grep  USERNAME   cut -f2 -d     for id in  IPCS M  do   ipcrm -m  id  done   or ipcrm -M to remove a shared memory segment by the key     bin bash  set IPCS M   ipcs -m   egrep  0x 0-9a-f    0-9      grep  USERNAME   cut -f1 -d     for id in  IPCS M  do   ipcrm -M  id  done   remove message queues  us ipcrm -q to remove a shared memory segment by the id     bin bash  set IPCS Q   ipcs -q   egrep  0x 0-9a-f    0-9      grep  USERNAME   cut -f2 -d     for id in  IPCS Q  do   ipcrm -q  id  done   or ipcrm -Q to remove a shared memory segment by the key     bin bash  set IPCS Q   ipcs -q   egrep  0x 0-9a-f    0-9      grep  USERNAME   cut -f1 -d     for id in  IPCS Q  do   ipcrm -Q  id  done   remove semaphores  us ipcrm -s to remove a semaphore segment by the id     bin bash  set IPCS S   ipcs -s   egrep  0x 0-9a-f    0-9      grep  USERNAME   cut -f2 -d     for id in  IPCS S  do   ipcrm -s  id  done   or ipcrm -S to remove a semaphore segment by the key     bin bash  set IPCS S   ipcs -s   egrep  0x 0-9a-f    0-9      grep  USERNAME   cut -f1 -d     for id in  IPCS S  do   ipcrm -S  id  done

User · Answer

bin bash ipcs -m   grep  whoami    awk    print  2      xargs -n1 ipcrm -m ipcs -s   grep  whoami    awk    print  2      xargs -n1 ipcrm -s ipcs -q   grep  whoami    awk    print  2      xargs -n1 ipcrm -q

User · Answer

Here  save and try this script  kill ipcs sh  on your shell      bin bash  ME  whoami   IPCS S  ipcs -s   egrep  0x 0-9a-f    0-9      grep  ME   cut -f2 -d     IPCS M  ipcs -m   egrep  0x 0-9a-f    0-9      grep  ME   cut -f2 -d     IPCS Q  ipcs -q   egrep  0x 0-9a-f    0-9      grep  ME   cut -f2 -d       for id in  IPCS M  do   ipcrm -m  id  done  for id in  IPCS S  do   ipcrm -s  id  done  for id in  IPCS Q  do   ipcrm -q  id  done   We use it whenever we run IPCS programs in the university student server  Some people don t always cleanup so   it s needed  P

User · Answer

1 line will do all  For message queue   ipcs -q   sed    d  1 2d     awk    print  Removing    2  system  ipcrm -q    2       ipcs -q will give the records of message queues   sed    d  1 2d    will remove last blank line     d   and first two header lines   1 2d    awk will do the rest i e  printing and removing using command  ipcrm -q  w r t  the value of column 2  coz  2

User · Answer

I don t know how to delete all at once  but you can use ipcs to list resources  and then use loop and delete with ipcrm  This should work  but it needs a little work  I remember that I made it work once in class

User · Answer

to remove all shared memory segments on FreeBSD     bin sh for i in   ipcs -m   awk    print  2      sed 1 2d   do     echo  ipcrm -m  i      ipcrm -m  i done   to remove all semaphores     bin sh for i in   ipcs -s   awk    print  2      sed 1 2d   do     echo  ipcrm -s  i      ipcrm -s  i done

User · Answer

Since you mentioned that you re working on a NFS system  do you have access to those semaphores and shared memory  I think you misunderstood what they are  they are an API code that enables processes to communicate with each other  semaphores are a solution for preventing race conditions and for threads to communicate with each other  in simple answer  they do not leave any residue on any filesystem   Unless you are using an socket or a pipe  Do you have the necessary permissions to remove them  why are they on an NFS system   Hope this helps  Best regards  Tom

User · Answer

This works on my Mac OS   for n in  ipcs -b -m   egrep  m   awk    print  2       do ipcrm -m  n  done

User · Answer

ipcs -s   grep  USERNAME   perl -e  while   lt STDIN gt      a split   s     print  ipcrm sem  a 1       or   ipcs -s   grep  USERNAME   awk     print  2       xargs ipcrm sem   Change  USERNAME to a real username

[linux] Delete all SYSTEM V shared memory and semaphores on UNIX-like systems

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