Me revoilà, succès de l'opération (enfin je crois)
Bloc de code:
-bash-3.2# diskutil rename disk21s2 Data
Volume on disk21s2 renamed to Data
-bash-3.2# diskutil resizeVolume disk21s2 150g jhfs+ macOS 0b
Resizing to 150000000000 bytes and adding 1 partition
Started partitioning on disk21s2 Data
Verifying the disk
Verifying file system
Volume was successfully unmounted
Performing fsck_hfs -fn -x /dev/rdisk21s2
Checking Journaled HFS Plus volume
Checking extents overflow file
Checking catalog file
Checking multi-linked files
Checking catalog hierarchy
Checking extended attributes file
Checking volume bitmap
Checking volume information
The volume Data appears to be OK
File system check exit code is 0
Restoring the original state found as mounted
Resizing
Shrinking file system
Modifying partition map
Initialized /dev/rdisk21s5 as a 52 GB case-insensitive HFS Plus volume with a 8192k journal
Mounting disk
Finished partitioning on disk21s2 Data
/dev/disk21 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.1 GB disk21
1: EFI EFI 209.7 MB disk21s1
2: Apple_HFS Data 150.0 GB disk21s2
3: Apple_HFS macOS 55.8 GB disk21s5
4: Microsoft Basic Data 300go 293.6 GB disk21s3
-bash-3.2# cp -av /Volumes/"Macintosh HD"/Users/celestin/Desktop /Volume/Data
cp: /Volume/Data: No such file or directory
cp: /Volumes/Macintosh HD/Users/celestin/Desktop: unable to copy extended attributes to /Volume/Data: No such file or directory
/Volumes/Macintosh HD/Users/celestin/Desktop -> /Volume/Data
cp: /Volume/Data/.DS_Store: No such file or directory
cp: /Volume/Data/.localized: No such file or directory
cp: /Volume/Data/.QT-01f7-d142f4b2-bfffc5a8-00: No such file or directory
cp: /Volume/Data/.QT-0d55-d112cb6f-bfffc5a8-00: No such file or directory
cp: /Volume/Data/.STRAVINSKI_Quatre_études_pour_orchestre.mscz,: No such file or directory
... [le code prend tout mon bureau comme ça mais c'était impossible à envoyer]