bash create dir with sequential numbers

问题

I am creating a script to run on OS X which will be run often by a novice user, and so want to protect a directory structure by creating a fresh one each time with an n+1 over the last:

target001 with the next run creating target002

I have so far:

lastDir=$(find /tmp/target* | tail -1 | cut -c 6-)
let n=$n+1
mkdir "$lastDir""$n"

However, the math isn't working here.

回答1:

No pipes and subprocesses:

targets=( /tmp/target* )                # all dirs in an array
lastdir=${targets[@]: (-1):1}           # select filename from last array element
lastdir=${lastdir##*/}                  # remove path
lastnumber=${lastdir/target/}           # remove 'target'
lastnumber=00$(( 10#$lastnumber + 1 ))  # increment number (base 10), add leading zeros

mkdir /tmp/target${lastnumber: -3}      # make dir; last 3 chars from lastnumber

A version with 2 parameters:

path='/tmp/x/y/z'                       # path without last part
basename='target'                       # last part

targets=( $path/${basename}* )          # all dirs in an array
lastdir=${targets[@]: (-1):1}           # select path from last entry
lastdir=${lastdir##*/}                  # select filename
lastnumber=${lastdir/$basename/}        # remove 'target'
lastnumber=00$(( 10#$lastnumber + 1 ))  # increment number (base 10), add leading zeros

mkdir $path/$basename${lastnumber: -3}  # make dir; last 3 chars from lastnumber

回答2:

What about mktemp?

Create  a  temporary  file  or directory, safely, and print its name.
TEMPLATE must contain at least 3 consecutive `X's in last  component.
If  TEMPLATE  is  not  specified, use tmp.XXXXXXXXXX, and --tmpdir is
implied.  Files are created u+rw, and directories u+rwx, minus  umask
restrictions.

回答3:

Use this line to calculate the new sequence number:

...
n=$(printf "%03d" $(( 10#$n + 1 )) )
mkdir "$lastDir""$n"

10# to force base 10 arithmetic. Provided $n beeing the last secuence already e.g. "001".

回答4:

Complete solution using extended test [[ and BASH_REMATCH :

[[ $(find /tmp/target* | tail -1) =~ ^(.*)([0-9]{3})$ ]]
mkdir $(printf "${BASH_REMATCH[1]}%03d" $(( 10#${BASH_REMATCH[2]} + 1 )) )

Provided /tmp/target001 is your directory pattern.

回答5:

Like this:

lastDir=$(find /tmp/target* | tail -1)
let n=1+${lastDir##/tmp/target}
mkdir /tmp/target$(printf "%03d" $n)

来源：https://stackoverflow.com/questions/16228018/bash-create-dir-with-sequential-numbers