unx13.htm

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<P>exit</P>

<TD>

<P>Exit from the current shell</P>

<TR>

<TD>

<P>fg</P>

<TD>

<P>Switch a job to foreground execution</P>

<TR>

<TD>

<P>foreach</P>

<TD>

<P>Looping control statement</P>

<TR>

<TD>

<P>glob</P>

<TD>

<P>Echo arguments to standard output</P>

<TR>

<TD>

<P>goto</P>

<TD>

<P>Alter the order of command execution</P>

<TR>

<TD>

<P>hashstat</P>

<TD>

<P>Print hash table statistics</P>

<TR>

<TD>

<P>history</P>

<TD>

<P>List command history</P>

<TR>

<TD>

<P>if</P>

<TD>

<P>Conditional execution</P>

<TR>

<TD>

<P>jobs</P>

<TD>

<P>List active jobs</P>

<TR>

<TD>

<P>kill</P>

<TD>

<P>Signal a process</P>

<TR>

<TD>

<P>limit</P>

<TD>

<P>Respecify maximum resource limits</P>

<TR>

<TD>

<P>login</P>

<TD>

<P>Invoke the system login procedure</P>

<TR>

<TD>

<P>logout</P>

<TD>

<P>Exit from a login shell</P>

<TR>

<TD>

<P>newgrp</P>

<TD>

<P>Change your group ID</P>

<TR>

<TD>

<P>nice</P>

<TD>

<P>Control background process dispatch priority</P>

<TR>

<TD>

<P>nohup</P>

<TD>

<P>Prevent termination on logout</P>

<TR>

<TD>

<P>notify</P>

<TD>

<P>Request notification of background job status changes</P>

<TR>

<TD>

<P>onintr</P>

<TD>

<P>Process interrupt within a shell script</P>

<TR>

<TD>

<P>popd</P>

<TD>

<P>Return to a previous directory</P>

<TR>

<TD>

<P>pushd</P>

<TD>

<P>Change directory with pushdown stack</P>

<TR>

<TD>

<P>rehash</P>

<TD>

<P>Rehash the directory search path</P>

<TR>

<TD>

<P>repeat</P>

<TD>

<P>Repetitively execute a command</P>

<TR>

<TD>

<P>set</P>

<TD>

<P>Display or change a variable</P>

<TR>

<TD>

<P>setenv</P>

<TD>

<P>Set environment variable</P>

<TR>

<TD>

<P>shift</P>

<TD>

<P>Shift parameters</P>

<TR>

<TD>

<P>source</P>

<TD>

<P>Interpret a script in the current shell</P>

<TR>

<TD>

<P>stop</P>

<TD>

<P>Stop a background job</P>

<TR>

<TD>

<P>suspend</P>

<TD>

<P>Stop the current shell</P>

<TR>

<TD>

<P>switch</P>

<TD>

<P>Conditional execution</P>

<TR>

<TD>

<P>time</P>

<TD>

<P>Time a command</P>

<TR>

<TD>

<P>umask</P>

<TD>

<P>Display or set the process file creation mask</P>

<TR>

<TD>

<P>unalias</P>

<TD>

<P>Delete a command alias</P>

<TR>

<TD>

<P>unhash</P>

<TD>

<P>Disable use of the hash table</P>

<TR>

<TD>

<P>unlimit</P>

<TD>

<P>Cancel a previous limit command</P>

<TR>

<TD>

<P>unset</P>

<TD>

<P>Delete shell variables</P>

<TR>

<TD>

<P>unsetenv</P>

<TD>

<P>Delete environment variables</P>

<TR>

<TD>

<P>wait</P>

<TD>

<P>Wait for background jobs to finish</P>

<TR>

<TD>

<P>while</P>

<TD>

<P>Looping control</P>

<TR>

<TD>

<P>%job</P>

<TD>

<P>Foreground execution</P>

<TR>

<TD>

<P>@</P>

<TD>

<P>Expression evaluation</P></TABLE>

<H5 ALIGN="CENTER">

<CENTER><A ID="I10" NAME="I10">

<FONT SIZE=3><B>Executing Simple Commands</B>

<BR></FONT></A></CENTER></H5>

<P>The most common form of input to the shell is the simple command, where a command name is followed by any number of arguments. For example, in the following command line

<BR></P>

<PRE>% chdir <I>dirname</I></PRE>

<P>chdir is the command and <I>dirname</I> is the argument. It is the responsibility of the command, not the shell, to interpret the arguments. Many commands, but certainly not all, take the form

<BR></P>

<PRE>% command -options filenames</PRE>

<P>Although the shell does not interpret the arguments of the command, the shell does make some interpretation of the input line before passing the arguments to the command. Special characters entered on a command line cause the shell to redirect input and 

output, start a different command, search the directories for filename patterns, substitute variable data, and substitute the output of other commands.

<BR></P>

<H5 ALIGN="CENTER">

<CENTER><A ID="I11" NAME="I11">

<FONT SIZE=3><B>Entering Multiple Commands on One Line</B>

<BR></FONT></A></CENTER></H5>

<P>Ordinarily, the shell interprets the first word of command input as the command name and the rest of the input as arguments to that command. The semicolon (;) directs the shell to interpret the word following the symbol as a new command, with the rest 
of the input as arguments to the new command. For example, the command line

<BR></P>

<PRE>% who -H; df -v; ps -e</PRE>

<P>is the equivalent of

<BR></P>

<PRE>% who -H

% df -v