File System Disk info | Boot | Disk usage | Opened files | Mount/remount | Mount SMB | Mount image | Burn ISO | Create image | Memory disk | Disk performance Permissions Change permission and ownership with chmod and chown. The default umask can be changed for all users in /etc/profile for Linux or /etc/login.conf for FreeBSD. The default umask is usually 022. The umask is subtracted from 777, thus umask 022 results in a permission 0f 755. 1 --x execute # Mode 764 = exec/read/write | read/write | read 2 -w- write # For: |-- Owner --| |- Group-| |Oth| 4 r-- read ugo=a u=user, g=group, o=others, a=everyone # chmod [OPTION] MODE[,MODE] FILE # MODE is of the form [ugoa]*([-+=]([rwxXst])) # chmod 640 /var/log/maillog # Restrict the log -rw-r----- # chmod u=rw,g=r,o= /var/log/maillog # Same as above # chmod -R o-r /home/* # Recursive remove other readable for all users # chmod u+s /path/to/prog # Set SUID bit on executable (know what you do!) # find / -perm -u+s -print # Find all programs with the SUID bit # chown user:group /path/to/file # Change the user and group ownership of a file # chgrp group /path/to/file # Change the group ownership of a file # chmod 640 `find ./ -type f -print` # Change permissions to 640 for all files # chmod 751 `find ./ -type d -print` # Change permissions to 751 for all directories Disk information # diskinfo -v /dev/ad2 # information about disk (sector/size) FreeBSD # hdparm -I /dev/sda # information about the IDE/ATA disk (Linux) # fdisk /dev/ad2 # Display and manipulate the partition table # smartctl -a /dev/ad2 # Display the disk SMART info Boot FreeBSD To boot an old kernel if the new kernel doesn't boot, stop the boot at during the count down. # unload # load kernel.old # boot System mount points/Disk usage # mount | column -t # Show mounted file-systems on the system # df # display free disk space and mounted devices # cat /proc/partitions # Show all registered partitions (Linux) Disk usage # du -sh * # Directory sizes as listing # du -csh # Total directory size of the current directory # du -ks * | sort -n -r # Sort everything by size in kilobytes # ls -lSr # Show files, biggest last Who has which files opened This is useful to find out which file is blocking a partition which has to be unmounted and gives a typical error of: # umount /home/ umount: unmount of /home # umount impossible because a file is locking home failed: Device busy FreeBSD and most Unixes # fstat -f /home # for a mount point # fstat -p PID # for an application with PID # fstat -u user # for a user name Find opened log file (or other opened files), say for Xorg: # ps ax | grep Xorg | awk '{print $1}' 1252 # fstat -p 1252 USER CMD PID FD MOUNT INUM MODE SZ|DV R/W root Xorg 1252 root / 2 drwxr-xr-x 512 r root Xorg 1252 text /usr 216016 -rws--x--x 1679848 r root Xorg 1252 0 /var 212042 -rw-r--r-- 56987 w The file with inum 212042 is the only file in /var: # find -x /var -inum 212042 /var/log/Xorg.0.log Linux Find opened files on a mount point with fuser or lsof: # fuser -m /home # List processes accessing /home # lsof /home COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME tcsh 29029 eedcoba cwd DIR 0,18 12288 1048587 /home/eedcoba (guam:/home) lsof 29140 eedcoba cwd DIR 0,18 12288 1048587 /home/eedcoba (guam:/home) About an application: ps ax | grep Xorg | awk '{print $1}' 3324 # lsof -p 3324 COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME Xorg 3324 root 0w REG 8,6 56296 12492 /var/log/Xorg.0.log About a single file: # lsof /var/log/Xorg.0.log COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME Xorg 3324 root 0w REG 8,6 56296 12492 /var/log/Xorg.0.log Mount/remount a file system For example the cdrom. If listed in /etc/fstab: # mount /cdrom Or find the device in /dev/ or with dmesg FreeBSD # mount -v -t cd9660 /dev/cd0c /mnt # cdrom # mount_cd9660 /dev/wcd0c /cdrom # other method # mount -v -t msdos /dev/fd0c /mnt # floppy Entry in /etc/fstab: # Device Mountpoint FStype Options Dump Pass# /dev/acd0 /cdrom cd9660 ro,noauto 0 0 To let users do it: # sysctl vfs.usermount=1 # Or insert the line "vfs.usermount=1" in /etc/sysctl.conf Linux # mount -t auto /dev/cdrom /mnt/cdrom # typical cdrom mount command # mount /dev/hdc -t iso9660 -r /cdrom # typical IDE # mount /dev/scd0 -t iso9660 -r /cdrom # typical SCSI cdrom # mount /dev/sdc0 -t ntfs-3g /windows # typical SCSI Entry in /etc/fstab: /dev/cdrom /media/cdrom subfs noauto,fs=cdfss,ro,procuid,nosuid,nodev,exec 0 0 Mount a FreeBSD partition with Linux Find the partition number containing with fdisk, this is usually the root partition, but it could be an other BSD slice too. If the FreeBSD has many slices, they are the one not listed in the fdisk table, but visible in /dev/sda* or /dev/hda*. # fdisk /dev/sda # Find the FreeBSD partition /dev/sda3 * 5357 7905 20474842+ a5 FreeBSD # mount -t ufs -o ufstype=ufs2,ro /dev/sda3 /mnt /dev/sda10 = /tmp; /dev/sda11 /usr # The other slices Remount Remount a device without unmounting it. Necessary for fsck for example # mount -o remount,ro / # Linux # mount -o ro -u / # FreeBSD Copy the raw data from a cdrom into an iso image (default 512 blocksize might cause problems): # dd if=/dev/cd0c of=file.iso bs=2048 Virtualbox Allow a share on the host: # VBoxManage sharedfolder add "GuestName" --name "share" --hostpath "C:\hostshare" Mount share on guest (linux, FreeBSD) # sudo mount -t vboxsf share /home/vboxshare # -o uid=1000,gid=1000 (as appropriate) share /home/colin/share vboxsf defaults,uid=colin 0 0 # fstab entry OSX # diskutil list # List the partitions of a disk # diskutil unmountDisk /dev/disk1 # Unmount an entire disk (all volumes) # chflags hidden ~/Documents/folder # Hide folder (reverse with unhidden) Add swap on-the-fly Suppose you need more swap (right now), say a 2GB file /swap2gb (Linux only). # dd if=/dev/zero of=/swap2gb bs=1024k count=2000 # mkswap /swap2gb # create the swap area # swapon /swap2gb # activate the swap. It now in use # swapoff /swap2gb # when done deactivate the swap # rm /swap2gb Mount an SMB share Suppose we want to access the SMB share myshare on the computer smbserver, the address as typed on a Windows PC is \\smbserver\myshare\. We mount on /mnt/smbshare. Warning> cifs wants an IP or DNS name, not a Windows name. Linux/OSX # smbclient -U user -I 192.168.16.229 -L //smbshare/ # List the shares # mount -t smbfs -o username=winuser //smbserver/myshare /mnt/smbshare # mount -t cifs -o username=winuser,password=winpwd //192.168.16.229/myshare /mnt/share Mound Samba share through ssh tunnel # ssh -C -f -N -p 20022 -L 445:127.0.0.1:445 me@server # connect on 20022, tunnel 445 # mount -t smbfs //colin@localhost/colin ~/mnt # mount_smbfs //colin:mypassword@127.0.0.1/private /Volumes/private # I use this on OSX + ssh Additionally with the package mount.cifs it is possible to store the credentials in a file, for example /home/user/.smb: username=winuser password=winpwd And mount as follow: # mount -t cifs -o credentials=/home/user/.smb //192.168.16.229/myshare /mnt/smbshare FreeBSD Use -I to give the IP (or DNS name); smbserver is the Windows name. # smbutil view -I 192.168.16.229 //winuser@smbserver # List the shares # mount_smbfs -I 192.168.16.229 //winuser@smbserver/myshare /mnt/smbshare Mount an image # hdiutil mount image.iso # OS X Linux loop-back # mount -t iso9660 -o loop file.iso /mnt # Mount a CD image # mount -t ext3 -o loop file.img /mnt # Mount an image with ext3 fs FreeBSD With memory device (do # kldload md.ko if necessary): # mdconfig -a -t vnode -f file.iso -u 0 # mount -t cd9660 /dev/md0 /mnt # umount /mnt; mdconfig -d -u 0 # Cleanup the md device Or with virtual node: # vnconfig /dev/vn0c file.iso; mount -t cd9660 /dev/vn0c /mnt # umount /mnt; vnconfig -u /dev/vn0c # Cleanup the vn device Solaris and FreeBSD with loop-back file interface or lofi: # lofiadm -a file.iso # mount -F hsfs -o ro /dev/lofi/1 /mnt # umount /mnt; lofiadm -d /dev/lofi/1 # Cleanup the lofi device Create and burn an ISO image This will copy the cd or DVD sector for sector. Without conv=notrunc, the image will be smaller if there is less content on the cd. See below and the dd examples. # dd if=/dev/hdc of=/tmp/mycd.iso bs=2048 conv=notrunc Use mkisofs to create a CD/DVD image from files in a directory. To overcome the file names restrictions: -r enables the Rock Ridge extensions common to UNIX systems, -J enables Joliet extensions used by Microsoft systems. -L allows ISO9660 filenames to begin with a period. # mkisofs -J -L -r -V TITLE -o imagefile.iso /path/to/dir # hdiutil makehybrid -iso -joliet -o dir.iso dir/ # OS X On FreeBSD, mkisofs is found in the ports in sysutils/cdrtools. Burn a CD/DVD ISO image FreeBSD FreeBSD does not enable DMA on ATAPI drives by default. DMA is enabled with the sysctl command and the arguments below, or with /boot/loader.conf with the following entries: hw.ata.ata_dma="1" hw.ata.atapi_dma="1" Use burncd with an ATAPI device (burncd is part of the base system) and cdrecord (in sysutils/cdrtools) with a SCSI drive. # burncd -f /dev/acd0 data imagefile.iso fixate # For ATAPI drive # cdrecord -scanbus # To find the burner device (like 1,0,0) # cdrecord dev=1,0,0 imagefile.iso Linux Also use cdrecord with Linux as described above. Additionally it is possible to use the native ATAPI interface which is found with: # cdrecord dev=ATAPI -scanbus And burn the CD/DVD as above. dvd+rw-tools The dvd+rw-tools package (FreeBSD: ports/sysutils/dvd+rw-tools) can do it all and includes growisofs to burn CDs or DVDs. The examples refer to the dvd device as /dev/dvd which could be a symlink to /dev/scd0 (typical scsi on Linux) or /dev/cd0 (typical FreeBSD) or /dev/rcd0c (typical NetBSD/OpenBSD character SCSI) or /dev/rdsk/c0t1d0s2 (Solaris example of a character SCSI/ATAPI CD-ROM device). There is a nice documentation with examples on the FreeBSD handbook chapter 18.7http://www.freebsd.org/handbook/creating-dvds.html. # -dvd-compat closes the disk # growisofs -dvd-compat -Z /dev/dvd=imagefile.iso # Burn existing iso image # growisofs -dvd-compat -Z /dev/dvd -J -R /p/to/data # Burn directly Convert a Nero .nrg file to .iso Nero simply adds a 300Kb header to a normal iso image. This can be trimmed with dd. # dd bs=1k if=imagefile.nrg of=imagefile.iso skip=300 Convert a bin/cue image to .iso The little bchunk programhttp://freshmeat.net/projects/bchunk/ can do this. It is in the FreeBSD ports in sysutils/bchunk. # bchunk imagefile.bin imagefile.cue imagefile.iso Create a file based image For example a partition of 1GB using the file /usr/vdisk.img. Here we use the vnode 0, but it could also be 1. FreeBSD # dd if=/dev/random of=/usr/vdisk.img bs=1K count=1M # mdconfig -a -t vnode -f /usr/vdisk.img -u 0 # Creates device /dev/md1 # bsdlabel -w /dev/md0 # newfs /dev/md0c # mount /dev/md0c /mnt # umount /mnt; mdconfig -d -u 0; rm /usr/vdisk.img # Cleanup the md device The file based image can be automatically mounted during boot with an entry in /etc/rc.conf and /etc/fstab. Test your setup with # /etc/rc.d/mdconfig start (first delete the md0 device with # mdconfig -d -u 0). Note however that this automatic setup will only work if the file image is NOT on the root partition. The reason is that the /etc/rc.d/mdconfig script is executed very early during boot and the root partition is still read-only. Images located outside the root partition will be mounted later with the script /etc/rc.d/mdconfig2. /boot/loader.conf: md_load="YES" /etc/rc.conf: # mdconfig_md0="-t vnode -f /usr/vdisk.img" # /usr is not on the root partition /etc/fstab: (The 0 0 at the end is important, it tell fsck to ignore this device, as is does not exist yet) /dev/md0 /usr/vdisk ufs rw 0 0 It is also possible to increase the size of the image afterward, say for example 300 MB larger. # umount /mnt; mdconfig -d -u 0 # dd if=/dev/zero bs=1m count=300 >> /usr/vdisk.img # mdconfig -a -t vnode -f /usr/vdisk.img -u 0 # growfs /dev/md0 # mount /dev/md0c /mnt # File partition is now 300 MB larger Linux # dd if=/dev/zero of=/usr/vdisk.img bs=1024k count=1024 # mkfs.ext3 /usr/vdisk.img # mount -o loop /usr/vdisk.img /mnt # umount /mnt; rm /usr/vdisk.img # Cleanup Linux with losetup /dev/zero is much faster than urandom, but less secure for encryption. # dd if=/dev/urandom of=/usr/vdisk.img bs=1024k count=1024 # losetup /dev/loop0 /usr/vdisk.img # Creates and associates /dev/loop0 # mkfs.ext3 /dev/loop0 # mount /dev/loop0 /mnt # losetup -a # Check used loops # umount /mnt # losetup -d /dev/loop0 # Detach # rm /usr/vdisk.img Create a memory file system A memory based file system is very fast for heavy IO application. How to create a 64 MB partition mounted on /memdisk: FreeBSD # mount_mfs -o rw -s 64M md /memdisk # umount /memdisk; mdconfig -d -u 0 # Cleanup the md device md /memdisk mfs rw,-s64M 0 0 # /etc/fstab entry Linux # mount -t tmpfs -osize=64m tmpfs /memdisk Disk performance Read and write a 1 GB file on partition ad4s3c (/home) # time dd if=/dev/ad4s3c of=/dev/null bs=1024k count=1000 # time dd if=/dev/zero bs=1024k count=1000 of=/home/1Gb.file # hdparm -tT /dev/hda # Linux only