Mercurial > hg > toybox
view toys/posix/echo.c @ 1531:3ff823086c99 draft
Teach ln -f to leave original target alone if link creation fails.
Suggested by Ashwini Sharma, I wound up implementing it by creating the new
link at a temporary name and renaming it over the old one instead of renaming
the old file out of the way and putting it back if it failed.
(Because "mkdir -p one/one/blah && ln -sf /bin/one one" would otherwise
rename one/one out of the way and only notice it can't delete it way at the
end when recovery's darn awkward, vs create new thing and if rename fails
(including EISDIR) that's the main error path. And yes the temporary name
is in the same directory as the destination so we never rename between mounts.)
link over the old one instead of renaming the old file and renaming it back.
author | Rob Landley <rob@landley.net> |
---|---|
date | Wed, 22 Oct 2014 17:11:06 -0500 |
parents | 95cb37adb024 |
children |
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/* echo.c - echo supporting -n and -e. * * Copyright 2007 Rob Landley <rob@landley.net> * * See http://opengroup.org/onlinepubs/9699919799/utilities/echo.html USE_ECHO(NEWTOY(echo, "^?en", TOYFLAG_BIN)) config ECHO bool "echo" default y help usage: echo [-ne] [args...] Write each argument to stdout, with one space between each, followed by a newline. -n No trailing newline. -e Process the following escape sequences: \\ backslash \0NNN octal values (1 to 3 digits) \a alert (beep/flash) \b backspace \c stop output here (avoids trailing newline) \f form feed \n newline \r carriage return \t horizontal tab \v vertical tab \xHH hexadecimal values (1 to 2 digits) */ #define FOR_echo #include "toys.h" void echo_main(void) { int i = 0, out; char *arg, *c; for (;;) { arg = toys.optargs[i]; if (!arg) break; if (i++) putchar(' '); // Should we output arg verbatim? if (!(toys.optflags & FLAG_e)) { xprintf("%s", arg); continue; } // Handle -e for (c = arg;;) { if (!(out = *(c++))) break; // handle \escapes if (out == '\\' && *c) { int slash = *(c++), n = unescape(slash); if (n) out = n; else if (slash=='c') goto done; else if (slash=='0') { out = 0; while (*c>='0' && *c<='7' && n++<3) out = (out*8)+*(c++)-'0'; } else if (slash=='x') { out = 0; while (n++<2) { if (*c>='0' && *c<='9') out = (out*16)+*(c++)-'0'; else { int temp = tolower(*c); if (temp>='a' && temp<='f') { out = (out*16)+temp-'a'+10; c++; } else break; } } // Slash in front of unknown character, print literal. } else c--; } putchar(out); } } // Output "\n" if no -n if (!(toys.optflags&FLAG_n)) putchar('\n'); done: xflush(); }