Integer arithmetics with environment variables in Bash

Here there's the trivial problem type: I have a collection of files enumerated with an index with format %03i, according to the usual C-like syntax, e.g., fileName001.dat fileName002.dat fileName003.dat .... fileName00N.dat I need to rename these files such that the second file in that series gets index 003, the 3rd file gets index 004 and so on. I essentially need to increase of one unit the value of each file index and then print it in the right format. Integer arithmetics is possible in Bash using the arithmetic evaluation compound command (( <expression> )) where <expression> is the arithmetic expression involving environment variables previously assigned integer values. To solve the previous problem, export I=2 J=$((I+1)) echo $J 3 printf -v COUNTERNEW "%03d" "$J" echo $COUNTERNEW 003 printf -v COUNTEROLD "%03d" "$I" mv fileName${COUNTEROLD}.dat fileName${COUNTERNEW}.dat See more information about the arithmetic operation compound command at http://wiki.bash-hackers.org/syntax/ccmd/arithmetic_eval.

String operators for processing environment variables in Bash

String operators for processing environment variables:

http://www.linuxjournal.com/article/8919

Bash printf command

The printf command is very useful for formatting expressions in Bash.

printf -v VAR <format> <expression>

See more information at the URL http://wiki.bash-hackers.org/commands/builtin/printf.