Log rotation by number of files instead of date

at first

I often delete the log file 7 days ago and use the date as a condition like rotation, This time I made a bash sample when rotating by specifying the number.

Files to be rotated

The file to rotate this time is It will be rotated in the format of server.log.YYYY-MM-DD.

/var/log/server.log #Latest file /var/log/server.log.2020-03-25 /var/log/server.log.2020-03-24 /var/log/server.log.2020-03-23 /var/log/server.log.2020-03-22

Implementation

    #!/bin/bash

    ROTATE_GEN=7             #Rotation generation (7 left this time)
    LOG=/var/log/server.log  #Target file

    #Save files with date
    mv ${LOG} ${LOG}.`date +"%Y-%m-%d"` 

    #Current number of files(FILE_CNT) -Number of generations(ROTATE_GEN)
    # =Number of files to delete(RM_CNT)
    FILE_CNT=`ls -1t ${LOG}.* | wc -l`
    RM_CNT=`expr ${FILE_CNT} - ${ROTATE_GEN}`

    # RM_Delete as many files as there are CNTs
    if [[ $RM_CNT -gt 0 ]] ; then
     ls -1t ${LOG}.* | tail -n ${RM_CNT} | xargs rm -f
    fi

Supplement

• The ls option is '1' instead of'l'