which command
觀看 help
執行
$ which -h顯示
Illegal option -h
Usage: /usr/bin/which [-a] args執行
$ which --help顯示
Illegal option --
Usage: /usr/bin/which [-a] args觀看版本
執行
$ which --version顯示
Illegal option --
Usage: /usr/bin/which [-a] args觀看 manpage
執行
$ whatis which顯示
which (1) - locate a command執行
$ man which會看到「說明」。
查詢 which 放在那個位置
執行
$ whereis which顯示
which: /usr/bin/which /bin/which /usr/share/man/man1/which.1.gz執行
$ which which顯示
/usr/bin/which執行
$ which -a which顯示
/usr/bin/which
/bin/which執行
$ type which顯示
which is hashed (/usr/bin/which)執行
$ type -a which顯示
which is /usr/bin/which
which is /bin/which執行
$ ls /usr/bin/which -l顯示
lrwxrwxrwx 1 root root 10 Apr 24 2016 /usr/bin/which -> /bin/which執行
$ stat /usr/bin/which顯示
File: '/usr/bin/which' -> '/bin/which'
Size: 10 Blocks: 0 IO Block: 4096 symbolic link
Device: 822h/2082d Inode: 4195706 Links: 1
Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2016-12-23 20:17:47.509825046 +0800
Modify: 2016-04-24 00:13:14.455049698 +0800
Change: 2016-04-24 00:13:14.455049698 +0800
Birth: -執行
$ file /usr/bin/which顯示
/usr/bin/which: symbolic link to /bin/which執行
$ file /bin/which顯示
/bin/which: POSIX shell script, ASCII text executable執行下面指令，來觀看「/usr/bin/which」的內容，會看到「/bin/which」的內容。
$ less /usr/bin/which執行下面指令，來觀看「/bin/which」的內容。
$ less /bin/which查詢 which 屬於那個套件
執行
$ dpkg -S /usr/bin/which或是執行
$ dpkg -S $(which which)顯示
dpkg-query: no path found matching pattern /usr/bin/which執行
$ dpkg -S /bin/which顯示
$ debianutils: /bin/which執行
$ dpkg -S $(which -a which)顯示
dpkg-query: no path found matching pattern /usr/bin/which
debianutils: /bin/which執行
$ grep '/usr/bin/which' /var/lib/dpkg/info/* -R -n顯示
/var/lib/dpkg/info/debianutils.postinst:14: if [ ! -e /usr/bin/which ]
/var/lib/dpkg/info/debianutils.postinst:16: ln -s /bin/which /usr/bin/which
/var/lib/dpkg/info/debianutils.postrm:11: if test -L /usr/bin/which; then
/var/lib/dpkg/info/debianutils.postrm:12: rm /usr/bin/which
/var/lib/dpkg/info/keyboard-configuration.postinst:8:# The same as /usr/bin/which - in order to make "which" available before執行下面指令 (多加了 -A 3)
$ grep '/usr/bin/which' /var/lib/dpkg/info/* -R -n -A 3顯示
/var/lib/dpkg/info/debianutils.postinst:14: if [ ! -e /usr/bin/which ]
/var/lib/dpkg/info/debianutils.postinst-15- then
/var/lib/dpkg/info/debianutils.postinst:16: ln -s /bin/which /usr/bin/which
/var/lib/dpkg/info/debianutils.postinst-17- fi
/var/lib/dpkg/info/debianutils.postinst-18- ;;
/var/lib/dpkg/info/debianutils.postinst-19-
--
/var/lib/dpkg/info/debianutils.postrm:11: if test -L /usr/bin/which; then
/var/lib/dpkg/info/debianutils.postrm:12: rm /usr/bin/which
/var/lib/dpkg/info/debianutils.postrm-13- fi
/var/lib/dpkg/info/debianutils.postrm-14- ;;
/var/lib/dpkg/info/debianutils.postrm-15- upgrade|failed-upgrade|purge|abort-install|abort-upgrade)
--
/var/lib/dpkg/info/keyboard-configuration.postinst:8:# The same as /usr/bin/which - in order to make "which" available before
/var/lib/dpkg/info/keyboard-configuration.postinst-9-# /usr is mounted
/var/lib/dpkg/info/keyboard-configuration.postinst-10-which () {
/var/lib/dpkg/info/keyboard-configuration.postinst-11- local IFS執行
$ view +14 /var/lib/dpkg/info/debianutils.postinst或是執行
$ vi +14 /var/lib/dpkg/info/debianutils.postinst開啟檔案後，就會將游標定位在第14行。
或是執行下面指令，觀看「/var/lib/dpkg/info/debianutils.postinst」這個檔案的「14行~17行」
$ cat /var/lib/dpkg/info/debianutils.postinst | sed -n '14,17p'或是執行
$ sed -n '14,17p' /var/lib/dpkg/info/debianutils.postinst顯示
if [ ! -e /usr/bin/which ]
then
ln -s /bin/which /usr/bin/which
fi表示「/usr/bin/which」這個檔案，是安裝「debianutils」這個套件時，
透過「/var/lib/dpkg/info/debianutils.postinst」這個「MaintainerScripts」產生的。
使用範例
執行
$ which which顯示
/usr/bin/which執行
$ which -a which顯示
/usr/bin/which
/bin/which搭配「dpkg -S」來使用
執行
$ dpkg -S $(which ls)顯示
coreutils: /bin/ls表示「/bin/ls」是屬於「coreutils」這個套件。
執行
$ dpkg -S $(which -a which)顯示
dpkg-query: no path found matching pattern /usr/bin/which
debianutils: /bin/which表示「/bin/which」是屬於「debianutils」這個套件。
註：
關於「$(command)」的用法，
請執行「$ info bash -n 'Command Substitution'」閱讀相關文件的內容，
也可以從「Bash Reference Manual / 3.5.4 Command Substitution」找到。
也可以執行「$ man bash」查詢「Command Substitution」。