z/OS V1R9.0 UNIX System Services Command ... - Christian Grothoff

Examples
The directory path name is always relative to the current root. If a nested chroot
command is in effect, the directory path name is still relative to the current (new)
root of the running process.
In order for your process to operate properly after the chroot is issued, you need to
have in your new root all the files that your program depends on. For example, if
your new root is /tmp and you issue an ls, you will get a not found error. To use ls
with /tmp as your new root, you will need a /tmp/bin with ls in it before you issue
the chroot command.
In addition, utilities that depend on locale-sensitive files (/usr/lib/nis/*) may be
unsuccessful if these files are not in the new root file system.
After chroot is issued, your current working directory is the new root (directory),
chroot does not change environment variables.
directory
Specifies the new root directory
command
Specifies a command to run with the chroot command
1. To run the ls command with the /tmp directory as the root file system, enter:
mkdir /tmp/bin
cp /bin/ls /tmp/bin
chroot /tmp ls
2. To run a child shell with another file system as the root file system (assuming
that /tmp is the mount point of a file system), enter:
mkdir /tmp/bin
cp /bin/sh /tmp/bin
chroot /tmp sh or chroot /tmp /bin/sh
This makes the directory name / (slash) refer to the /tmp for the duration of the
/bin/sh command. It also makes the original root file system inaccessible. The
file system on the /tmp file must contain the standard directories of a root file
system.
Running the /bin/sh command creates a child shell that runs as a separate
process from your original shell. Press the END OF FILE (Crtl-D) key sequence
or type exit to end the child shell and go back to where you were in the original
shell. This restores the environment of the original shell, including the meanings
of the . (current directory) and the / (root directory).
3. To create a file relative to the original root, not the new one, enter:
chroot Directory Command > file
For example, chroot /tmp ls > /bin/file will create the file in /bin/file.
Note: Redirection is handled by the current shell before chroot is executed.
4. To create a file relative to the new root, enter:
chroot Directory ’Command > file’
For example, chroot /tmp ’ls > /bin/file’ will create the file in /tmp/bin/file.
5. Examples of how the current root changes:
chroot
Chapter 2. Shell command descriptions 131