我正试图了解NUMBER_OF_IMAGES_TO_REMAIN=$((${2} - 1))
,特别是- 1
在这个脚本中的作用。
#!/bin/bash
# Copyright © 2017 Google Inc.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
IFS=$'nt'
set -eou pipefail
if [[ "$#" -ne 2 || "${1}" == '-h' || "${1}" == '--help' ]]; then
cat >&2 <<"EOF"
housekeeping_images.sh cleans up tagged or untagged images pushed for a given repository (an image name without a tag/digest)
and except the given number most recent images
USAGE:
housekeeping_images.sh REPOSITORY NUMBER_OF_IMAGES_TO_REMAIN
EXAMPLE
housekeeping_images.sh eu.gcr.io/YOUR_PROJECT/IMAGE_NAME 5
would clean up everything under the eu.gcr.io/test-project/php repository
pushed except for the 5 most recent images
EOF
exit 1
# elif [ ${2} -ge 0 ] 2>/dev/null; then
# echo "no number of images to remain given" >&2
# exit 1
fi
main() {
local C=0
IMAGE="${1}"
NUMBER_OF_IMAGES_TO_REMAIN=$((${2} - 1))
DATE=$(gcloud container images list-tags $IMAGE --limit=unlimited
--sort-by=~TIMESTAMP --format=json | TZ=/usr/share/zoneinfo/UTC jq -r '.['$NUMBER_OF_IMAGES_TO_REMAIN'].timestamp.datetime | sub("(?<before>.*):"; .before ) | strptime("%Y-%m-%d %H:%M:%S%z") | mktime | strftime("%Y-%m-%d")')
for digest in $(gcloud container images list-tags $IMAGE --limit=unlimited --sort-by=~TIMESTAMP
--filter="timestamp.datetime < '${DATE}'" --format='get(digest)'); do
(
set -x
gcloud container images delete -q --force-delete-tags "${IMAGE}@${digest}"
)
let C=C+1
done
echo "Deleted ${C} images in ${IMAGE}." >&2
}
main "${1}" ${2}
使用脚本注释中的示例:
housekeeping_images.sh eu.gcr.io/YOUR_PROJECT/IMAGE_NAME 5
脚本中的最后一行:
main "${1}" ${2}
变为:
main "eu.gcr.io/YOUR_PROJECT/IMAGE_NAME" 5
在main()
函数中,变量分配:
IMAGE="${1}"
NUMBER_OF_IMAGES_TO_REMAIN=$((${2} - 1))
变成:
IMAGE="eu.gcr.io/YOUR_PROJECT/IMAGE_NAME"
NUMBER_OF_IMAGES_TO_REMAIN=$((5 - 1))
第二个变量接收最终值:
NUMBER_OF_IMAGES_TO_REMAIN=4