Shell scripting sub string extraction

Question

I have a set of file names following some pattern. I need to insert a date into the filename string. Now, I also have some files following a slightly different pattern. I would like to know how can a single string match both the requirements.

eg. filenames are like:

abcTrade_proj.dat 
abcPosition_proj.dat 
abcAccount_proj.dat

I'm using below string to construnct the filename like abcTrade_yyyymmdd_proj.dat

${filename%_*}_${DATE}_${filename#*_}

Now, apart from the above file patterns, I have the pattern:

abc_pqr_Account_proj.dat 
abc_pqr_Trade_proj.dat

All i need to do is cut the string till the last _, insert the date and append the string that is there after _, for both the type of file patterns.

Is there any solution for both situations?

it is like, i need to split the string based upon last _. so that irrespective of no.of unserscores in the first part of the filename, i can always split based upon the last uderscore. — user1999315
– user1999315, Commented Jun 14, 2014 at 10:05

ebo · Accepted Answer · 2014-06-14 10:34:46Z

1

If possible, you could use sed to construct the new name as follows:

DATE=$(date +%Y%m%d)
echo "abcTrade_pqr_proj.dat" | sed "s/^\(.*\)_\([^_]*\)/\1_${DATE}_\2/g"

which results in:

abcTrade_pqr_20140101_proj.dat

edited Jun 14, 2014 at 10:34

answered Jun 14, 2014 at 9:44

ebo

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2 Comments

Qeole Over a year ago

May I suggest export DATE=$(date +%Y%m%d) for the date of current day, at same format?

user1999315 Over a year ago

THanks Eric. sed can be used to cut the strings. I shall test and let you know.

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