Notes of Introduction to OS Abstractions Using Plan 9 from Bell Labs(II)

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man: section 1 is for commands, section 8 is forcommands not commonly used by users (i.e., they are intended to administer the system), and

section 2 is for C functions and libraries.

To read a manual page found at a particular

section, you can type the section number and the page name after the man command, like in

; man 1 ls

lookman is used to search manual.

sig displays the signature, i.e., the prototype for a C function documented in section 2 of the manual.

Flag -m asks ls to print the name of the user who last modified a file, along with the file name.

cp accepts more than one (source) file name to copy to the destination file name.

We can see a dump of the bytes kept within that file using the program xd (hexadecimal dump). This program reads a file and writes its contents so that it is

easy for us to read. Option -b asks xd to print the contents as a series of bytes:

term% xd -b TODO

0000000 63 6f 70 79 20 6d 6b 64 65 70 20 66 72 6f 6d 20

0000010 6c 65 66 66 65 20 28 2d 72 20 66 6c 61 67 29 0a

0000020 0a

0000021

Adding option -c, the program prints the character for each byte when feasible:

term% xd -b -c TODO

0000000 63 6f 70 79 20 6d 6b 64 65 70 20 66 72 6f 6d 20

0 c o p y m k d e p f r o m

0000010 6c 65 66 66 65 20 28 2d 72 20 66 6c 61 67 29 0a

10 l e f f e ( - r f l a g ) /n

0000020 0a

20 /n

0000021

The command nm (name list) displays the names of symbols (i.e., procedure names, variables) that are contained or required by our object and executable files.