| <head> |
| <title>arg(3) - Plan 9 from User Space</title> |
| <meta content="text/html; charset=utf-8" http-equiv=Content-Type> |
| </head> |
| <body bgcolor=#ffffff> |
| <table border=0 cellpadding=0 cellspacing=0 width=100%> |
| <tr height=10><td> |
| <tr><td width=20><td> |
| <tr><td width=20><td><b>ARG(3)</b><td align=right><b>ARG(3)</b> |
| <tr><td width=20><td colspan=2> |
| <br> |
| <p><font size=+1><b>NAME </b></font><br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| ARGBEGIN, ARGEND, ARGC, ARGF, EARGF, arginit, argopt – process |
| option letters from argv<br> |
| |
| </table> |
| <p><font size=+1><b>SYNOPSIS </b></font><br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>#include <u.h><br> |
| #include <libc.h> |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| </font></tt> |
| <tt><font size=+1>ARGBEGIN { <br> |
| char *ARGF(); <br> |
| char *EARGF(code); <br> |
| Rune ARGC(); <br> |
| } ARGEND <br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| </font></tt> |
| <tt><font size=+1>extern char *argv0; <br> |
| </font></tt> |
| </table> |
| <p><font size=+1><b>DESCRIPTION </b></font><br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| These macros assume the names <i>argc</i> and <i>argv</i> are in scope; see |
| <a href="../man3/exec.html"><i>exec</i>(3)</a>. <i>ARGBEGIN</i> and <i>ARGEND</i> surround code for processing program |
| options. The code should be the cases of a C switch on option |
| characters; it is executed once for each option character. Options |
| end after an argument <tt><font size=+1>−−</font></tt>, before an argument <tt><font size=+1>−</font></tt>, or |
| before an argument that doesn’t begin with <tt><font size=+1>−</font></tt>. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| The function macro <i>ARGC</i> returns the current option character, |
| as an integer. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| The function macro <i>ARGF</i> returns the current option argument: a |
| pointer to the rest of the option string if not empty, or the |
| next argument in <i>argv</i> if any, or 0. <i>ARGF</i> must be called just once |
| for each option that takes an argument. The macro <i>EARGF</i> is like |
| <i>ARGF</i> but instead of returning zero runs <i>code</i> and, if that |
| returns, calls <a href="../man3/abort.html"><i>abort</i>(3)</a>. A typical value for <i>code</i> is <tt><font size=+1>usage()</font></tt>, |
| as in <tt><font size=+1>EARGF(usage())</font></tt>. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| After <i>ARGBEGIN</i>, <i>argv0</i> is a copy of <tt><font size=+1>argv[0]</font></tt> (conventionally the |
| name of the program). |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| After <i>ARGEND</i>, <i>argv</i> points at a zero-terminated list of the remaining |
| <i>argc</i> arguments.<br> |
| |
| </table> |
| <p><font size=+1><b>EXAMPLE </b></font><br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| This C program can take option <tt><font size=+1>b</font></tt> and option <tt><font size=+1>f</font></tt>, which requires |
| an argument.<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>#include <u.h><br> |
| #include <libc.h><br> |
| void<br> |
| main(int argc, char *argv[])<br> |
| {<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| char *f;<br> |
| print("%s", argv[0]);<br> |
| ARGBEGIN {<br> |
| case 'b':<br> |
| print(" −b");<br> |
| break;<br> |
| case 'f':<br> |
| print(" −f(%s)", (f=ARGF())? f: "no arg");<br> |
| break;<br> |
| default:<br> |
| print(" badflag('%c')", ARGC());<br> |
| } ARGEND<br> |
| print(" %d args:", argc);<br> |
| while(*argv)<br> |
| print(" '%s'", *argv++);<br> |
| print("\n");<br> |
| exits(nil);<br> |
| |
| </table> |
| }<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| </font></tt> |
| |
| </table> |
| Here is the output from running the command <tt><font size=+1>prog −bffile1 −r −f |
| file2 arg1 arg2<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| prog −b −f(file1) badflag('r') −f(file2) 2 args: 'arg1' 'arg2' |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| </table> |
| </font></tt> |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| |
| |
| </table> |
| |
| </table> |
| <p><font size=+1><b>SOURCE </b></font><br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>/usr/local/plan9/include/libc.h<br> |
| </font></tt> |
| </table> |
| |
| <td width=20> |
| <tr height=20><td> |
| </table> |
| <!-- TRAILER --> |
| <table border=0 cellpadding=0 cellspacing=0 width=100%> |
| <tr height=15><td width=10><td><td width=10> |
| <tr><td><td> |
| <center> |
| <a href="../../"><img src="../../dist/spaceglenda100.png" alt="Space Glenda" border=1></a> |
| </center> |
| </table> |
| <!-- TRAILER --> |
| </body></html> |
