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CentOS mailing list <centos@xxxxxxxxxx> writes: I had at one point copied a large number of files between drives and did not use the -p and thus the timestamps were all set to the date of the copy. I did not catch this, and deleted the source. So I 'lived' with it and have since changed many files. Well, yesterday I found a good backup of many of those files and I want to restore them to their proper dates. cp -p -u is exactly the opposite of what I want. I want to copy only if the source files have an earlier date than the destination files. The source files are just an old copy on another drive that I found when cleaning up things... SRC="" /> DST=/the/working/tree export SRC DST find "$SRC" -type f -print | while read A; do [ "${A}" -ot "${DST}${A##$SRC}" ] && /bin/touch -r ${A} "${DST}${A##$SRC}"; done Note that using this syntax, the two variables cannot be set in-place on the same command line as "find ..."; it only seems to work for me if they're exported as environment variables. A more expanded version of the same, with commentary: cat > fix_timestamps.sh << __EOF__ #!/bin/sh ### Scans a source directory for files, setting the dates of same-named files in a target directory ### Adam Thompson <athompson@xxxxxxxx> 2007-Aug-07 # Source directory - no need for trailing slash SRC="" /> # Target directory - no need for trailing slash DST=/the/working/tree # Locate all _files_ only find "$SRC" -type f -print | ( # subshell not necessary, only here for readability # read each line of input from the pipe into $A while read A; do # if's can be shortened to && most times # Proceed only if source file is OlderThan target file if [ "${A}" -ot "${DST}${A##$SRC}" ]; then # Proceed only if target file exists # Probably being paranoid, since -ot should have already failed... if [ -f "${DST}${A##$SRC}" ]; then # Use "touch" to reset the timestamp on the file \ # instead of re-copying the data # "-r" == "--reference", uses the source file's \ # timestamp to set the destination file's timestamp /bin/touch -r ${A} "${DST}${A##$SRC}" fi fi done ) __EOF__ Obviously the one-liner above is going to be marginally faster, especially on slower CPUs, but the difference should be minimal - bash isn't that much of a CPU hog. -Adam Thompson Divisional IT Department, St. James-Assiniboia School Division 150 Moray St., Winnipeg, MB, R3J 3A2 athompson@xxxxxxxx / tel: (204) 837-5886 x222 / fax: (204) 885-3178 |
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