Shell脚本输出格式优化请求：去除空行及多余空格

Let's tackle those extra spaces and empty lines in your script's output—here's how to get clean, properly formatted results:

What's Wrong With the Original Script #

The main issue is how you're collecting and printing results. When you store loop output in the mount_check array, empty entries can sneak in (from mount points that are mounted, since your loop only outputs something when they're not). Plus, using echo ${mount_check[*]} joins array elements with spaces, leading to messy spacing and empty lines when there are gaps in the array.

Solution 1: Direct Output (Simplest & Most Efficient) #

Skip the array entirely and print results immediately as you check each mount point. This avoids array-related formatting headaches:

#!/bin/bash

# Filter relevant mount points from /etc/fstab (skip bind, swap, shm, comments, empty lines)
while IFS= read -r mount_point; do
    # Check if the mount point is unmounted (suppress findmnt's output)
    if ! findmnt -m "$mount_point" >/dev/null 2>&1; then
        echo "File system $mount_point is NOT mounted"
    fi
done < <(awk '!/bind|swap|shm/ && $1 !~/#|^$/ && !/^ +$/ { print $2 }' /etc/fstab)

Why This Works: #

• The while read loop processes each mount point one by one.
• findmnt -m "$mount_point" >/dev/null 2>&1 silences all output from findmnt—we only care about its exit status to know if the mount is missing.
• We print the message only when a mount point is unmounted, so no empty lines or extra spaces creep in.

Solution 2: Use Array Properly (If You Need to Store Results) #

If you must keep results in an array for later use, make sure you only add valid messages to the array, then print each element on its own line:

#!/bin/bash

# Get filtered mount points
fstable=( $(awk '!/bind|swap|shm/ && $1 !~/#|^$/ && !/^ +$/ { print $2 }' /etc/fstab))

# Initialize empty array to hold error messages
mount_check=()

for mount in "${fstable[@]}"; do
    if ! findmnt -m "$mount" >/dev/null 2>&1; then
        # Add only non-empty messages to the array
        mount_check+=("File system $mount is NOT mounted")
    fi
done

# Print each array element on a new line
printf '%s\n' "${mount_check[@]}"

Why This Works: #

• We explicitly add messages to the array only when a mount point is unmounted—no empty entries.
• printf '%s\n' "${mount_check[@]}" prints each array element on its own line, with no extra spacing.

Either approach will give you the clean output you want:

File system /abc is NOT mounted
File system /xyz is NOT mounted

内容的提问来源于stack exchange，提问作者rony thomas