最後更新: 2019-01-02

介紹

它的功能是校對/計算檔案完整性 (128 bit MD5 值)

目錄

• md5sum
• sha256sum
• cksum
• xxhash

md5sum

Syntax

md5sum [OPTION] [FILE]...

例子

1 查看某檔案的 md5 值

md5sum cartoon_list.txt

ab65da9ee3e50f6fdc04435cf29b65fd  cartoon_list.txt

2 為一個目錄下的所以檔案建立 checksum 檔

md5sum  ./folder/* > folder.md5

3 效對 checksum 檔內指定的檔案的正確性

md5sum -c squirrelmail-webmail-1.4.22.tar.gz.md5

squirrelmail-webmail-1.4.22.tar.gz: OK

當檔案被人修改過就會有如下結果

cartoon_list.txt: FAILED
md5sum: WARNING: 1 of 1 computed checksum did NOT match

4. 計算及校對一整個目錄

# 計算

cd /home/vhosts/datahunter.org

rm hash.txt

find web -type f -exec md5sum {} \; >> hash.txt

chmod 600 hash.txt

# 校對

md5sum -c hash.txt

其他

"0" 's md5sum

# -b, --binary               read in binary mode

# the two modes(text, binary) always produce same result

# outputting a ‘*’ flag

dd if=/dev/zero bs=10M count=10 2>/dev/null | md5sum -b

2f282b84e7e608d5852449ed940bfc51 *-

List

100 M   2f282b84e7e608d5852449ed940bfc51
1 GB    e5c834fbdaa6bfd8eac5eb9404eefdd4
1 GiB   cd573cfaace07e7949bc0c46028904ff

sha256sum

sha256sum --ignore-missing -c SHA256SUMS

cksum

Print CRC checksum and byte counts of each FILE

cksum [FILE]

ie.

cksum rd.gz

3095222862 6292398 rd.gz