linux command

linux command

1) NAME

ls - list directory contents
SYNOPSIS

ls [OPTION]... [FILE]...
DESCRIPTION

List information about the FILEs (the current directory by default). Sort entries alphabetically if none of -cftuSUX nor --sort.

















2) NAME

cp - copy files and directories
SYNOPSIS

cp [OPTION]... SOURCE DEST
cp [OPTION]... SOURCE... DIRECTORY
cp [OPTION]... --target-directory=DIRECTORY SOURCE...
DESCRIPTION

Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY.







3) NAME

mv - move (rename) files
SYNOPSIS

mv [OPTION]... SOURCE DEST
mv [OPTION]... SOURCE... DIRECTORY
mv [OPTION]... --target-directory=DIRECTORY SOURCE...
EXAMPLES

DESCRIPTION

Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY.






4) NAME

rm - remove files or directories
SYNOPSIS

rm [OPTION]... FILE...
EXAMPLES

DESCRIPTION

This manual page documents the GNU version of rm. rm removes each specified file.
By default, it does not remove directories. If a file is unwritable, the standard input is a tty,
and the -f or --force option is not given, rm prompts the user for whether to remove the file.
If the response does not begin with `y' or `Y', the file is skipped.







5) NAME

chmod - change file access permissions
Examples

SYNOPSIS

chmod [OPTION]... MODE[,MODE]... FILE...
chmod [OPTION]... OCTAL-MODE FILE...
chmod [OPTION]... --reference=RFILE FILE...
DESCRIPTION

This manual page documents the GNU version of chmod. chmod changes the permissions of each given file according to mode, which can be either a symbolic representation of changes to make, or an octal number representing the bit pattern for the new permissions.
The format of a symbolic mode is `[ugoa...][[+-=][rwxXstugo...]...][,...]'. Multiple symbolic operations can be given, separated by commas.

A combination of the letters `ugoa' controls which users' access to the file will be changed: the user who owns it (u), other users in the file's group (g), other users not in the file's group (o), or all users (a). If none of these are given, the effect is as if `a' were given, but bits that are set in the umask are not affected.

The operator `+' causes the permissions selected to be added to the existing permissions of each file; `-' causes them to be removed; and `=' causes them to be the only permissions that the file has.

The letters `rwxXstugo' select the new permissions for the affected users: read (r), write (w), execute (or access for directories) (x), execute only if the file is a directory or already has execute permission for some user (X), set user or group ID on execution (s), sticky (t), the permissions granted to the user who owns the file (u), the permissions granted to other users who are members of the file's group (g), and the permissions granted to users that are in neither of the two preceding categories (o).

A numeric mode is from one to four octal digits (0-7), derived by adding up the bits with values 4, 2, and 1. Any omitted digits are assumed to be leading zeros. The first digit selects the set user ID (4) and set group ID (2) and sticky (1) attributes. The second digit selects permissions for the user who owns the file: read (4), write (2), and execute (1); the third selects permissions for other users in the file's group, with the same values; and the fourth for other users not in the file's group, with the same values.

chmod never changes the permissions of symbolic links; the chmod system call cannot change their permissions. This is not a problem since the permissions of symbolic links are never used. However, for each symbolic link listed on the command line, chmod changes the permissions of the pointed-to file. In contrast, chmod ignores symbolic links encountered during recursive directory traversals.

STICKY FILES

On older Unix systems, the sticky bit caused executable files to be hoarded in swap space. This feature is not useful on modern VM systems, and the Linux kernel ignores the sticky bit on files. Other kernels may use the sticky bit on files for system-defined purposes. On some systems, only the superuser can set the sticky bit on files.
STICKY DIRECTORIES

When the sticky bit is set on a directory, files in that directory may be unlinked or renamed only by root or their owner. Without the sticky bit, anyone able to write to the directory can delete or rename files. The sticky bit is commonly found on directories, such as /tmp, that are world-writable.
OPTIONS

Change the mode of each FILE to MODE.

-c, --changes
like verbose but report only when a change is made
-f, --silent, --quiet
suppress most error messages
-v, --verbose
output a diagnostic for every file processed
--reference=RFILE
use RFILE's mode instead of MODE values
-R, --recursive
change files and directories recursively
--help
display this help and exit
--version
output version information and exit
Each MODE is one or more of the letters ugoa, one of the symbols +-= and one or more of the letters rwxXstugo.





6) NAME

kill - terminate a process
SYNOPSIS

kill [ -s signal | -p ] [ -a ] [ -- ] pid ...
kill -l [ signal ]
DESCRIPTION

The command kill sends the specified signal to the specified process or process group. If no signal is specified, the TERM signal is sent. The TERM signal will kill processes which do not catch this signal. For other processes, it may be necessary to use the KILL (9) signal, since this signal cannot be caught.
Most modern shells have a builtin kill function, with a usage rather similar to that of the command described here. The `-a' and `-p' options, and the possibility to specify pids by command name is a local extension.

OPTIONS

pid...
Specify the list of processes that kill should signal. Each pid can be one of five things:
n
where n is larger than 0. The process with pid n will be signaled.
0
All processes in the current process group are signaled.
-1
All processes with pid larger than 1 will be signaled.
-n
where n is larger than 1. All processes in process group n are signaled. When an argument of the form `-n' is given, and it is meant to denote a process group, either the signal must be specified first, or the argument must be preceded by a `--' option, otherwise it will be taken as the signal to send.
commandname
All processes invoked using that name will be signaled.
-s signal
Specify the signal to send. The signal may be given as a signal name or number.
-l
Print a list of signal names. These are found in /usr/include/linux/signal.h
-a
Do not restrict the commandname-to-pid conversion to processes with the same uid as the present process.
-p
Specify that kill should only print the process id (pid) of the named processes, and not send any signals.






7) NAME

ps - report process status
EXAMPLES

SYNOPSIS

ps [options]

DESCRIPTION

ps gives a snapshot of the current processes. If you want a repetitive update of this status, use top. This man page documents the /proc-based version of ps, or tries to.

COMMAND-LINE OPTIONS

This version of ps accepts several kinds of options.
Unix98 options may be grouped and must be preceeded by a dash.
BSD options may be grouped and must not be used with a dash.
GNU long options are preceeded by two dashes.