如何用Grep获取/dev/开头文件系统的使用率百分比？

Here are two reliable, straightforward ways to get the usage percentage for all filesystems starting with /dev/:

Option 1: Extending Your Original grep Approach #

You can build on your existing regex by first filtering lines that start with /dev/, then extracting the numeric percentage value:

df -h | grep "^/dev/" | grep -oP "(\d+(\.\d+)?(?=%))"

Breakdown of what each part does:

• df -h: Generates human-readable disk usage output
• grep "^/dev/": Filters only lines where the filesystem name starts with /dev/ (the ^ ensures it’s matched at the start of the line)
• The final grep -oP: Extracts the numeric percentage (including optional decimals) immediately before the % sign

Option 2: Using awk (Cleaner & More Efficient) #

awk lets you handle both filtering and extraction in a single command, which is often more efficient than chaining multiple greps:

df -h | awk '/^\/dev\// { sub(/%/, "", $5); print $5 }'

Breakdown:

• /^\/dev\//: Matches lines starting with /dev/ (we escape the / with \ because it’s the delimiter for awk regex)
• sub(/%/, "", $5): Removes the % character from the 5th column (this is the Use% column in df -h output)
• print $5: Prints the cleaned-up percentage value

Example Output #

If your df -h output includes lines like:

/dev/md2        1.8T  633G  1.1T  37% /
/dev/md0        976M   32M  894M  34% /boot

Both commands will output:

37
34

内容的提问来源于stack exchange，提问作者Harrison