Frequently used Unix commands -
1. Alias (to create a shortcut)
alias variable='foldername'
Example - alias sources='/opt/sources'
2. ssh (remote login program)
ssh username@hostname
Example - ssh abcd@10.10.10.10
abcd@10.10.10.10's password: password
ssh -t => force connection
ssh -v => verbose connection (print debugging messages)
3. scp (transfer files with ssh)
scp local_file(s) user@hostname:destination_directory
Example - scp jdk.zip abcd@10.10.10.10:/opt/sources/jdk
4. chmod (change mode)
chmod a+x abcd.sh
| Reference | Class | Description |
|---|
| u | user | the owner of the file |
| g | group | users who are members of the file's group |
| o | others | users who are neither the owner of the file nor members of the file's group |
| a | all | all three of the above, same as ugo |
| Operator | Description |
|---|
| + | adds the specified modes to the specified classes |
| - | removes the specified modes from the specified classes |
| = | the modes specified are to be made the exact modes for the specified class |
| Mode | Name | Description |
|---|
| r | read | read a file or list a directory's contents |
| w | write | write to a file or directory |
| x | execute | execute a file or recurse a directory tree |
| X | special execute | which is not a permission in itself but rather can be used instead of x. It applies execute permissions to directories regardless of their current permissions and applies execute permissions to a file which already has at least one execute permission bit already set (either user, group or other). It is only really useful when used with '+' and usually in combination with the -R option for giving group or other access to a big directory tree without setting execute permission on normal files (such as text files), which would normally happen if you just used "chmod -R a+rx .", whereas with 'X' you can do "chmod -R a+rX ." instead |
