命令tr
$ df -h
Filesystem Size Used Avail Use% Mounted on
udev 126G 0 126G 0% /dev
tmpfs 26G 4.0M 26G 1% /run
/dev/sda2 548G 50G 471G 10% /
tmpfs 126G 0 126G 0% /sys/fs/cgroup
/dev/sda1 511M 7.9M 504M 2% /boot/efi
/dev/sdb1 2.0T 4.7G 1.9T 1% /data
字母小写转大写
$ df -h | tr [:lower:] [:upper:]
FILESYSTEM SIZE USED AVAIL USE% MOUNTED ON
UDEV 126G 0 126G 0% /DEV
TMPFS 26G 4.0M 26G 1% /RUN
/DEV/SDA2 548G 50G 471G 10% /
TMPFS 126G 0 126G 0% /SYS/FS/CGROUP
/DEV/SDA1 511M 7.9M 504M 2% /BOOT/EFI
/DEV/SDB1 2.0T 4.7G 1.9T 1% /DATA
$ df -h | tr a-z A-Z
字母大写转小写
$ df -h | tr [:upper:] [:lower:]
$ df -h | tr A-Z a-z