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Last update Feb 2, 2003
CHMOD: Read/Write File Attributes
chmod changes or displays the attributes for a particular file.
Command syntax:
chmod {(+|-)attribute} [file...]
file is the file or files of interest. Wildcards are accepted.
Using + before an attribute turns on the attribute.
Using - turns off the attribute.
The attributes are:
- R Read only
- H Hidden
- S System
- V Volume label
- D Subdirectory
- A Archive
Example: This line makes myfile.exe a read-only file:
chmod +R myfile.exe
If no attributes are specified,
chmod displays (but does not change) the file's
attributes, in this form:
__A__SHR 0x27 IO.SYS
Mnemonic characters denote attributes that are "on"; underscored
characters indicate that an attribute is "off."
Thus, chmod can be handy for finding hidden and system files:
chmod *.*
DIFF: Compare Files
diff compares two text files and displays any
lines that are different.
diffdir switches... file1 file2
switches:
- -c
- Show context around differences
- -e
- Set off differences with <<>>
- -i[macro]
- Set off differences with #if macro/#else/#endif
- -w
- Ignore trailing whitespace when comparing lines
DIFFDIR: Compare Directories
diffdir recursively compares the contents of two directory trees.
Files are compared by reading the files and comparing them
byte-for-byte.
All files, including hidden and system files, are compared.
diffdir switches... dir1 dir2
switches:
- -v Verbose
The output of the program will list files that are different
from dir1 to dir2, prefixed by a character:
- - File exists in dir1 but not in dir2.
- + File exists in dir2 but not in dir1.
- # File exists in both dir1 and dir2, but
has different contents.
It's useful for:
- Verifying that a backup actually does contain exactly
the same files with the same content.
- Determining what files in a release package have changed
from one version to the next.
- Determining what files on a disk were modified by an
installation program (by comparing with a backup).
- Detecting if files on a disk were tampered with by comparing
with a known good backup.
FLPYIMG: Read/Write Floppy Image
flpyimg will read, write, and verify entire floppy
disk images, or just the boot sector. It's useful for backing
up boot floppies, or for preparing boot floppies with a
custom operating system.
Reading a floppy image from drive: and writing it to file:
flpyimg switches... drive: file
Reading a floppy image from file and writing it to drive:
flpyimg switches... file drive:
- -b Boot sector only, not the entire disk.
- -h Help
- -v Verify that file matches disk contents.
Examples
Read the entire contents of disk a: and write it to
the file foo.img.
flpyimg a: foo.img
Read the first 512 bytes of boot.img and write
it to the boot sector of disk b:.
flpyimg -b boot.img b:
Read the entire contents of disk b: and verify that
it matches
the file foo.img.
flpyimg -v b: foo.img
Notes
- flpyimg is a DOS program, meaning it will not
handle long file names.
- The only disk drives flpyimg will write to are
drives A: and B:, to avoid accidental destruction of
drive C:.
- The floppy disk must already have been properly formatted
before flpyimg can write to it.
- Windows XP will not read 160Kb single sided DOS disks at all,
at least not disks formatted by DOS 1.0.
DOS 1.0 does not set the BIOS parameter block (BPB) correctly
in the boot sector.
Windows 95 will read them.
WHEREIS: Search For Files
whereis searches a directory tree or the entire disk
for specified files.
whereis filespec
Searches the entire disk for files matching filespec.
filespec can contain ? and * wildcards.
whereis directory filespec
Recursively searches directory and all its subdirectories
for files matching filespec.
filespec can contain ? and * wildcards.
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