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| linux:start [2026/07/02 21:19] – [File operations] mh | linux:start [2026/07/02 21:26] (current) – [File operations] mh |
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| === Mass renaming === | === Mass renaming === |
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| Uppercase .JPG to lowercase .jpg | __**Changing an extension:**__ |
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| <code bash> | <code bash> |
| </code> | </code> |
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| Or changing a prefix: | __**Changing a prefix:**__ |
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| <code bash> | <code bash> |
| </code> | </code> |
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| * @'"prefix"*.png'@ targets only files beginning with the selected prefix, so unrelated files in the folder are ignored. | * ''"prefix"*.png'' targets only files beginning with the selected prefix, so unrelated files in the folder are ignored. |
| * @'${i/#prefix/another prefix}'@ replaces only the prefix at the beginning of the filename. If the same text appears later in the filename, it is left untouched. | * ''${i/#prefix/another prefix}'' replaces only the prefix at the beginning of the filename. If the same text appears later in the filename, it is left untouched. |
| * In Bash parameter expansion, the @'#'@ before @'prefix'@ means “match only at the start of the variable value”. Without @'#'@, Bash would replace the first matching occurrence anywhere in the filename. | * In Bash parameter expansion, the ''#'' before ''prefix'' means “match only at the start of the variable value”. Without ''#'', Bash would replace the first matching occurrence anywhere in the filename. |
| * @'mv -n'@ prevents overwriting an existing file if the renamed target already exists. | * ''mv -n'' prevents overwriting an existing file if the renamed target already exists. |
| * @'--'@ tells @'mv'@ that everything after it is a filename, not an option. This protects against unusual filenames starting with @'-'@. | * ''--'' tells ''mv'' that everything after it is a filename, not an option. This protects against unusual filenames starting with ''-''. |
| * @'"$i"'@ keeps the original filename safely quoted, so spaces and special characters in filenames are preserved. | * ''"$i"'' keeps the original filename safely quoted, so spaces and special characters in filenames are preserved. |
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| Alternative (rename tool): | __**Alternative (rename tool):**__ |
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| <code bash> | <code bash> |
| rename 's/\.JPG$/.jpg/' *.JPG | rename 's/\.JPG$/.jpg/' *.JPG |
| </code> | </code> |
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| | * Use the ''for ... done'' + ''mv -n --'' loop for safe, explicit prefix renaming. |
| | * Use ''rename'' for concise regex-based changes, especially extension changes such as ''.JPG'' to ''.jpg''. |
| | * On Linux Mint / Ubuntu, ''rename 's/\.JPG$/.jpg/' *.JPG'' usually works because the available ''rename'' is the Perl-style tool. |
| | * The ''rename'' command is not fully portable across all Linux distributions, because different systems may ship different versions with different syntax. |
| | * For safety, preview first with ''rename -n 's/\.JPG$/.jpg/' *.JPG''. |
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