Can someone suggest on how to rename the file name:




Is there a single line statement to do the rename in Unix?

  • 9
    Do you assume that .tar.gz is an extension? Also, welcome to U&L! – EKons Oct 11 '16 at 11:02
  • 2
    Do you really mean Unix as opposed to Linux? Which Unix? – terdon Oct 11 '16 at 12:05
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    The obvious answer is mv head.body.date.txt head_body_date.txt. If you have other restrictions or real examples, then please update your question with these. As it stands now, it's unclear whether the question refers to a file with that explicit name, a single directory where all files have a particular format, or if you want to search a directory hierarchy for particular names and change these. – Kusalananda Jul 16 '18 at 12:43

Iterate over the filenames, and use Parameter expansion for conversion:

for f in *.*.*.txt; do i="${f%.txt}"; echo mv -i -- "$f" "${i//./_}.txt"; done

The parameter expansion pattern, ${f//./_} replaces all .s with _s in the filename ($f).

The above will do a dry-run, to let the actual renaming take place, remove echo:

for f in *.*.*.txt; do i="${f%.txt}"; mv -i -- "$f" "${i//./_}.txt"; done

If you want to deal with any extension, not just .txt:

for f in *.*.*.*; do pre="${f%.*}"; suf="${f##*.}"; \
                     echo mv -i -- "$f" "${pre//./_}.${suf}"; done

After checking remove echo for actual action:

for f in *.*.*.*; do pre="${f%.*}"; suf="${f##*.}"; \
                     mv -i -- "$f" "${pre//./_}.${suf}"; done

Generic, for arbitrary number of dots, at least one:

for f in *.*; do pre="${f%.*}"; suf="${f##*.}"; \
                 mv -i -- "$f" "${pre//./_}.${suf}"; done
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  • is there a general way if there is an arbitrary number of dots ? – Ciprian Tomoiagă Oct 11 '16 at 9:21
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    @CiprianTomoiaga Do: for f in *.*; do ...; done – heemayl Oct 11 '16 at 9:26
  • I might suggest putting the *.* pattern straight in the example, since now the code looks like it works only with a fixed number of dots. – ilkkachu Oct 11 '16 at 11:23
  • @ilkkachu Fair enough, edited. – heemayl Oct 11 '16 at 11:26
  • Thank you so much heemay, it worked for me. and some learning! – S G Oct 11 '16 at 16:51

with perl based rename

$ rename -n 's/\.[^.]+$(*SKIP)(*F)|\./_/g' head.body.date.txt 
rename(head.body.date.txt, head_body_date.txt)
  • \.[^.]+$(*SKIP)(*F) skip this pattern and look for alternate matches
  • |\./_/g replace all . with _

Or, using negative lookahead

$ rename -n 's/\.(?![^.]+$)/_/g' head.body.date.txt 
rename(head.body.date.txt, head_body_date.txt)

Once this is okay, remove the -n option

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rename 's/\.(?=[^.]*\.)/_/g' *.txt

Uses regex replacement to find all but the last instance of . in the filename (non-capturing lookahead) and replace them with _. Generalises to *.* if you like.

(this particular version of rename seems to be installed via util-linux). I'm using Ubuntu 12.04 (yes, severely out of date machine).

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old=head.body.date.txt oldb=${old%.*} olde=${old##*.} ; \
mv -- "$old" "${oldb//./_}.${olde}"
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  • (1) You should use mv --, to guard against “old” filenames that begin with -. (2) You should put $old in quotes ("$old"), to guard against “old” filenames that contain spaces or characters that are special to the shell (like * and ?). (3) Your answer fails in the somewhat pathological case in which the extension contains an underscore: head.body.date.t_xt gets renamed to head_body_date_t.xt. – Scott Oct 12 '16 at 3:10
  • @Scott, thanks. The code is now tweaked as per all three items mentioned. – agc Oct 12 '16 at 4:02

Using mv, sed and rev in one line:

mv "head.body.date.txt" "$(echo head.body.date.txt | rev | sed 's/\./_/2g' | rev)"

If you want to apply it on all txt files in current rep, using globs seems tricky because of how mv works, but you can do a for loop in a one-liner:

for file in *.txt; do mv "$file" "$(echo $file | rev | sed 's/\./_/2g' | rev)"; done

Slightly longer, but you can match several patterns in your loop !

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  • 2
    (1) Arrghhh! Don’t do $(ls …); just do for file in *.txt. (2) You should use more quotes: mv "$file" "$(…)". – Scott Oct 12 '16 at 3:11
  • Thank you Scott, duly noted and edited ! I am still a youngster in shell, please be gentle ;) – Valentin B. Oct 12 '16 at 7:53
  • In hindsight, using rename like several others have suggested in their answers does sound simpler though... – Valentin B. Oct 12 '16 at 8:03
 mv head.body.date.txt head_body_date.txt

It is as simple as that for a single file at a time. You do no specify whether you would like this done recursively within a directory or to the whole directory at all, so that would be your most convenient, quick solution.

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