forked from openkylin/platform_build
41 lines
1.9 KiB
Plaintext
41 lines
1.9 KiB
Plaintext
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README for Android "acp" Command
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The "cp" command was judged and found wanting. The issues are:
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Mac OS X:
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- Uses the BSD cp, not the fancy GNU cp. It lacks the "-u" flag, which
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only copies files if they are newer than the destination. This can
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slow the build when copying lots of content.
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- Doesn't take the "-d" flag, which causes symlinks to be copied as
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links. This is the default behavior, so it's not all bad, but it
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complains if you supply "-d".
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MinGW/Cygwin:
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- Gets really weird when copying a file called "foo.exe", failing with
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"cp: skipping file 'foo.exe', as it was replaced while being copied".
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This only seems to happen when the source file is on an NFS/Samba
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volume. "cp" works okay copying from local disk.
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Linux:
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- On some systems it's possible to have microsecond-accurate timestamps
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on an NFS volume, and non-microsecond timestamps on a local volume.
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If you copy from NFS to local disk, your NFS files will always be
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newer, because the local disk time stamp is truncated rather than
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rounded up. This foils the "-u" flag if you also supply the "-p" flag
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to preserve timestamps.
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- The Darwin linker insists that ranlib be current. If you copy the
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library, the time stamp no longer matches. Preserving the time
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stamp is essential, so simply turning the "-p" flag off doesn't work.
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Futzing around these in make with GNU make functions is awkward at best.
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It's easier and more reliable to write a cp command that works properly.
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The "acp" command takes most of the standard flags, following the GNU
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conventions. It adds a "-e" flag, used when copying executables around.
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On most systems it is ignored, but on MinGW/Cygwin it allows "cp foo bar"
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to work when what is actually meant is "cp foo.exe bar.exe". Unlike the
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default Cygwin cp, "acp foo bar" will not find foo.exe unless you add
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the "-e" flag, avoiding potential ambiguity.
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