Resize /dev/shm

To increase or decrease /dev/shm filesystem size

1) Open /etc/fstab with vi or any text editor of your choice,

2) Locate the line of /dev/shm and use the tmpfs size option to specify your expected size,

e.g. 512MB:
tmpfs      /dev/shm      tmpfs   defaults,size=512m   0   0

e.g. 2GB:
tmpfs      /dev/shm      tmpfs   defaults,size=2g   0   0

The /etc/fstab content format is documented in man fstab and the tmpfs filesystem options can be found in man mount

3) To make change effective immediately, run this mount command to remount the /dev/shm filesystem:
mount -o remount /dev/shm