Question

我正在编写一个脚本，用于在命令行上将新用户添加到OS X系统。我知道我可以使用以下命令列出系统中所有用户ID的用户：

dscl . -list /Users UniqueID

给出了类似的东西：

xxxxxxx                         937
xxxxxxxx                        939
xxxxx                           940
xxxxxx                          941

如何从此输出中检索最大的用户ID以存储在变量中？

Answer 1

这将为您提供ID最高的行：

dscl . -list /Users UniqueID | sort -nr -k 2 | head -1

Answer 2

只需awk

即可轻松（高效）地完成此操作

awk '$2>m{m=$2}END{print m}' file

将其存储在变量do：

中

highestID=$(awk '$2>m{m=$2}END{print m}' file)

Answer 3

Scott Hunter和SiegeX的回答+一些Python的组合：

# Max User ID
MAXUID=`dscl . list /Users UniqueID | awk '$2>m{m=$2}END{print m}'`

# Next User ID
NEXTUID=$(( $MAXUID + 1 )) 

# Three Ways to Retrieve Specific User ID
UID=`id -u $USER`
UID=`dscl . list /Users/$USER | awk '{print $2}'`
UID=`python -c 'import pwd,os; print pwd.getpwnam(os.getenv("USER")).pw_uid'`


# Three Ways to Retrieve Max Group ID
MAXGID=`dscacheutil -q group | grep gid | awk '$2>n{n=$2}END{print n}'`
MAXGID=`dscl . list /Groups PrimaryGroupID | awk '$2>n{n=$2}END{print n}'`
MAXGID=`python -c 'import grp;print grp.getgrgid(max(g.gr_gid for g in grp.getgrall()))'`
   # notice the python method has a different max groupid
   # this is because nobody/nouser groups have negative values for PrimaryGroupID in dscl
   # but python gives these absolute values:
   # 2^32 = 4294967296
   #    if you subtract one you get 4294967295 (the max group id python returns)

# Two Ways to Retrieve Specific Group ID (i.e. staff)
STAFFGID=`dscl . read /Groups/staff PrimaryGroupID | awk '{print $2}'`
STAFFGID=`python -c 'import grp; print grp.getgrnam("staff").gr_gid'`

在Mac OS X中查找最高用户ID

3 个答案: