在我的计算机上，我安装了 NodeJS 和 Yarn。如果我打开一个新的命令行窗口，我可以成功使用它们各自的node和yarn命令。如果我which对它们使用，我会分别得到/usr/bin/node和/usr/bin/yarn。
我遇到的问题是当我采用以下脚本时：
#!/bin/bash
cd <directory with yarn package info>
yarn install
并通过 NodeJS 的子进程 API 运行它，我收到一条错误消息yarn: command not found
在尝试找出问题所在时，我首先检查了脚本中的路径并/usr/bin包含在内。然后，我在 shell 脚本中为这两个命令以及 python3 添加了 which。我需要的两个命令没有显示任何内容，而 python3 显示/usr/bin/python3。然后我从脚本中运行ls -l /usr/bin，与从普通 shell 运行相比，缺少大量链接和命令。
这可能是什么原因造成的？我已经用尽了我所有的 Linux 知识，唯一能想到的就是与用户/组或权限相关的问题。
编辑：$PATH 的输出是
/snap/<app_name>/x1/usr/sbin:
/snap/<app_name>/x1/usr/bin:
/snap/<app_name>/x1/sbin:
/snap/<app_name>/x1/bin:
/usr/local/sbin:
/usr/local/bin:
/usr/sbin:
/usr/bin:
/sbin:
/bin:
/usr/games:
/usr/local/games:
/snap/<app_name>/x1/gnome-platform/usr/bin
输出ls -l /usr/bin：
-rwxr-xr-x 1 root root 51384 Jan 18 2018 [
-rwxr-xr-x 1 root root 22696 Sep 27 2018 aa-enabled
-rwxr-xr-x 1 root root 22696 Sep 27 2018 aa-exec
-rwxr-xr-x 1 root root 22608 Mar 5 11:23 addpart
-rwxr-xr-x 1 root root 35032 Jan 18 2018 arch
lrwxrwxrwx 1 root root 4 Jul 7 05:47 awk -> mawk
-rwxr-xr-x 1 root root 55512 Jan 18 2018 b2sum
-rwxr-xr-x 1 root root 39096 Jan 18 2018 base32
-rwxr-xr-x 1 root root 39096 Jan 18 2018 base64
-rwxr-xr-x 1 root root 35000 Jan 18 2018 basename
-rwxr-xr-x 1 root root 7115 Jun 6 2019 bashbug
-rwxr-xr-x 1 root root 34952 May 3 06:30 bootctl
-rwxr-xr-x 1 root root 67672 May 3 06:30 busctl
lrwxrwxrwx 1 root root 3 May 23 2018 captoinfo -> tic
-rwxr-xr-x 1 root root 3329 Jun 4 12:25 catchsegv
-rwxr-xr-x 1 root root 853 Jul 15 2016 cautious-launcher
-rwxr-sr-x 1 root shadow 71816 Mar 22 2019 chage
lrwxrwxrwx 1 root root 11 Jun 18 2017 chardet3 -> chardetect3
-rwxr-xr-x 1 root root 389 Jun 18 2017 chardetect3
-rwxr-xr-x 1 root root 14336 Jan 22 08:40 chattr
-rwxr-xr-x 1 root root 63672 Jan 18 2018 chcon
-rwsr-xr-x 1 root root 76496 Mar 22 2019 chfn
-rwxr-xr-x 1 root root 30800 Mar 5 11:23 chrt
-rwsr-xr-x 1 root root 44528 Mar 22 2019 chsh
-rwxr-xr-x 1 root root 35000 Jan 18 2018 cksum
-rwxr-xr-x 1 root root 10240 May 23 2018 clear
-rwxr-xr-x 1 root root 10312 Jun 6 2019 clear_console
-rwxr-xr-x 1 root root 390 Jan 15 10:35 cloud-id
-rwxr-xr-x 1 root root 394 Jan 15 10:35 cloud-init
-rwxr-xr-x 1 root root 2108 Jan 14 14:27 cloud-init-per
-rwxr-xr-x 1 root root 47200 Aug 4 2017 cmp
-rwxr-xr-x 1 root root 39128 Jan 18 2018 comm
lrwxrwxrwx 1 root root 11 Jul 15 2016 compose -> run-mailcap
lrwxrwxrwx 1 root root 35 Aug 7 2018 console-conf -> ../share/subiquity/console-conf-tui
-rwxr-xr-x 1 root root 1565 Jul 7 05:45 core-sshd-host-keygen
-rwxr-xr-x 1 root root 6332 May 27 14:15 c_rehash
-rwxr-xr-x 1 root root 51416 Jan 18 2018 csplit
lrwxrwxrwx 1 root root 6 May 11 09:40 ctstat -> lnstat
-rwxr-xr-x 1 root root 43224 Jan 18 2018 cut
-rwxr-xr-x 1 root root 10224 Jun 11 13:25 dbus-cleanup-sockets
-rwxr-xr-x 1 root root 236584 Jun 11 13:25 dbus-daemon
-rwxr-xr-x 1 root root 22520 Jun 11 13:25 dbus-monitor
-rwxr-xr-x 1 root root 10224 Jun 11 13:25 dbus-run-session
-rwxr-xr-x 1 root root 26608 Jun 11 13:25 dbus-send
-rwxr-xr-x 1 root root 14320 Jun 11 13:25 dbus-update-activation-environment
-rwxr-xr-x 1 root root 10224 Jun 11 13:25 dbus-uuidgen
-rwxr-xr-x 1 root root 20142 Oct 25 2017 deb-systemd-helper
-rwxr-xr-x 1 root root 4434 Oct 25 2017 deb-systemd-invoke
-rwxr-xr-x 1 root root 22608 Mar 5 11:23 delpart
-rwxr-xr-x 1 root root 2550 Apr 1 2018 dh_bash-completion
-rwxr-xr-x 1 root root 145752 Aug 4 2017 diff
-rwxr-xr-x 1 root root 63704 Aug 4 2017 diff3
-rwxr-xr-x 1 root root 47296 Jan 18 2018 dircolors
-rwxr-xr-x 1 root root 30904 Jan 18 2018 dirname
-rwxr-xr-x 1 root root 153952 Sep 5 2019 dpkg-deb
-rwxr-xr-x 1 root root 100568 Jan 18 2018 du
-rwxr-xr-x 1 root root 7297 Apr 13 2018 ec2metadata
lrwxrwxrwx 1 root root 11 Jul 15 2016 edit -> run-mailcap
lrwxrwxrwx 1 root root 8 Jul 7 05:47 editor -> vim.tiny
-rwxr-xr-x 1 root root 35000 Jan 18 2018 env
lrwxrwxrwx 1 root root 8 Jul 7 05:47 ex -> vim.tiny
-rwxr-xr-x 1 root root 39128 Jan 18 2018 expand
-rwxr-sr-x 1 root shadow 22808 Mar 22 2019 expiry
-rwxr-xr-x 1 root root 47288 Jan 18 2018 expr
-rwxr-xr-x 1 root root 75992 Jan 18 2018 factor
-rwxr-xr-x 1 root root 18728 Mar 22 2019 faillog
-rwxr-xr-x 1 root root 26704 Mar 5 11:23 fallocate
-rwxr-xr-x 1 root root 238080 Nov 5 2017 find
-rwxr-xr-x 1 root root 30880 Mar 5 11:23 flock
-rwxr-xr-x 1 root root 43192 Jan 18 2018 fmt
-rwxr-xr-x 1 root root 35000 Jan 18 2018 fold
-rwxr-xr-x 1 root root 18512 Aug 9 2019 free
-rwxr-xr-x 1 root root 30856 Jun 4 12:25 getconf
-rwxr-xr-x 1 root root 31224 Jun 4 12:25 getent
-rwxr-xr-x 1 root root 14408 Mar 5 11:23 getopt
-rwsr-xr-x 1 root root 75824 Mar 22 2019 gpasswd
-rwxr-xr-x 1 root root 437264 Jan 10 2019 gpgv
-rwxr-xr-x 1 root root 35000 Jan 18 2018 groups
-rwxr-xr-x 1 root root 21883 Apr 13 2018 growpart
-rwxr-xr-x 1 root root 43224 Jan 18 2018 head
-rwxr-xr-x 1 root root 2514 Feb 2 2018 helpztags
-rwxr-xr-x 1 root root 30904 Jan 18 2018 hostid
-rwxr-xr-x 1 root root 18504 May 3 06:30 hostnamectl
lrwxrwxrwx 1 root root 7 Mar 5 11:23 i386 -> setarch
-rwxr-xr-x 1 root root 63744 Jun 4 12:25 iconv
-rwxr-xr-x 1 root root 43224 Jan 18 2018 id
-rwxr-xr-x 1 root root 59464 May 23 2018 infocmp
lrwxrwxrwx 1 root root 3 May 23 2018 infotocap -> tic
-rwxr-xr-x 1 root root 145664 Jan 18 2018 install
-rwxr-xr-x 1 root root 26704 Mar 5 11:23 ionice
-rwxr-xr-x 1 root root 26768 Mar 5 11:23 ipcmk
-rwxr-xr-x 1 root root 26704 Mar 5 11:23 ipcrm
-rwxr-xr-x 1 root root 51280 Mar 5 11:23 ipcs
lrwxrwxrwx 1 root root 19 Nov 11 2017 iptables-xml -> /sbin/xtables-multi
-rwxr-xr-x 1 root root 10280 Dec 30 2017 ischroot
-rwxr-xr-x 1 root root 47320 Jan 18 2018 join
lrwxrwxrwx 1 root root 16 Jul 7 05:47 jsondiff -> python3-jsondiff
lrwxrwxrwx 1 root root 17 Jul 7 05:47 jsonpatch -> python3-jsonpatch
lrwxrwxrwx 1 root root 19 Jul 7 05:47 jsonpointer -> python3-jsonpointer
lrwxrwxrwx 1 root root 18 Jul 7 05:47 jsonschema -> python3-jsonschema
-rwxr-xr-x 1 root root 4508 Jan 28 2018 kernel-install
-rwxr-xr-x 1 root root 43088 Mar 5 11:23 last
lrwxrwxrwx 1 root root 4 Mar 5 11:23 lastb -> last
-rwxr-xr-x 1 root root 18504 Mar 22 2019 lastlog
-rwxr-xr-x 1 root root 7786 Feb 25 2018 lcf
-rwxr-xr-x 1 root root 5422 Jun 4 12:25 ldd
lrwxrwxrwx 1 root root 9 Jul 7 05:46 less -> /bin/less
lrwxrwxrwx 1 root root 13 Jul 7 05:46 lessecho -> /bin/lessecho
lrwxrwxrwx 1 root root 13 Jul 7 05:46 lessfile -> /bin/lessfile
lrwxrwxrwx 1 root root 12 Jul 7 05:46 lesskey -> /bin/lesskey
lrwxrwxrwx 1 root root 13 Jul 7 05:46 lesspipe -> /bin/lesspipe
-rwxr-xr-x 1 root root 30904 Jan 18 2018 link
lrwxrwxrwx 1 root root 7 Mar 5 11:23 linux32 -> setarch
lrwxrwxrwx 1 root root 7 Mar 5 11:23 linux64 -> setarch
-rwxr-xr-x 1 root root 22888 May 11 09:40 lnstat
-rwxr-xr-x 1 root root 50592 Jun 4 12:25 locale
-rwxr-xr-x 1 root root 10240 Jan 30 06:28 locale-check
-rwxr-xr-x 1 root root 22600 May 3 06:30 localectl
-rwxr-xr-x 1 root root 338744 Jun 4 12:25 localedef
-rwxr-xr-x 1 root root 47792 Mar 5 11:23 logger
-rwxr-xr-x 1 root root 30904 Jan 18 2018 logname
-rwxr-xr-x 1 root root 10240 Jan 22 08:40 lsattr
-rwxr-xr-x 1 root root 71760 Mar 5 11:23 lscpu
-rwxr-xr-x 1 root root 71760 Mar 5 11:23 lsipc
-rwxr-xr-x 1 root root 35232 Mar 5 11:23 lslocks
-rwxr-xr-x 1 root root 63568 Mar 5 11:23 lslogins
-rwxr-xr-x 1 root root 43088 Mar 5 11:23 lsmem
-rwxr-xr-x 1 root root 38992 Mar 5 11:23 lsns
-rwxr-xr-x 1 root root 125416 Apr 3 2018 mawk
-rwxr-xr-x 1 root root 30864 Mar 5 11:23 mcookie
-rwxr-xr-x 1 root root 43224 Jan 18 2018 md5sum
lrwxrwxrwx 1 root root 6 Jan 18 2018 md5sum.textutils -> md5sum
-rwxr-xr-x 1 root root 10312 Mar 5 11:23 mesg
-rwxr-xr-x 1 root root 35098 Apr 9 2018 miniterm
-rwxr-xr-x 1 root root 63672 Jan 18 2018 mkfifo
-rwxr-xr-x 1 root root 189432 Jul 5 2018 mksquashfs
-rwxr-xr-x 1 root root 865 Jul 7 05:45 mkswapfile
-rwxr-xr-x 1 root root 26704 Mar 5 11:23 namei
lrwxrwxrwx 1 root root 4 Jul 7 05:47 nawk -> mawk
-rwsr-xr-x 1 root root 40344 Mar 22 2019 newgrp
-rwxr-xr-x 1 root root 35000 Jan 18 2018 nice
-rwxr-xr-x 1 root root 43288 Jan 18 2018 nl
-rwxr-xr-x 1 root root 35000 Jan 18 2018 nohup
-rwxr-xr-x 1 root root 35000 Jan 18 2018 nproc
-rwxr-xr-x 1 root root 31008 Mar 5 11:23 nsenter
-rwxr-xr-x 1 root root 26696 May 11 09:40 nstat
-rwxr-xr-x 1 root root 63736 Jan 18 2018 numfmt
-rwxr-xr-x 1 root root 67800 Jan 18 2018 od
-rwxr-xr-x 1 root root 723944 May 27 14:15 openssl
lrwxrwxrwx 1 root root 14 Jul 7 05:47 pager -> ../../bin/less
-rwxr-xr-x 1 root root 88144 Mar 5 11:23 partx
-rwsr-xr-x 1 root root 59640 Mar 22 2019 passwd
-rwxr-xr-x 1 root root 35032 Jan 18 2018 paste
-rwxr-xr-x 1 root root 35000 Jan 18 2018 pathchk
lrwxrwxrwx 1 root root 6 Oct 25 2018 pdb3 -> pdb3.6
lrwxrwxrwx 1 root root 23 Apr 17 20:56 pdb3.6 -> ../lib/python3.6/pdb.py
-rwxr-xr-x 2 root root 2097720 Nov 19 2018 perl
-rwxr-xr-x 2 root root 2097720 Nov 19 2018 perl5.26.1
-rwxr-xr-x 1 root root 26712 Aug 9 2019 pgrep
-rwxr-xr-x 1 root root 39128 Jan 18 2018 pinky
lrwxrwxrwx 1 root root 5 Aug 9 2019 pkill -> pgrep
-rwxr-xr-x 1 root root 18656 Jun 4 12:25 pldd
-rwxr-xr-x 1 root root 30808 Aug 9 2019 pmap
-rwxr-xr-x 1 root root 71960 Jan 18 2018 pr
lrwxrwxrwx 1 root root 11 Jul 15 2016 print -> run-mailcap
-rwxr-xr-x 1 root root 30904 Jan 18 2018 printenv
-rwxr-xr-x 1 root root 51384 Jan 18 2018 printf
-rwxr-xr-x 1 root root 35424 Mar 5 11:23 prlimit
lrwxrwxrwx 1 root root 28 Oct 15 2018 probert -> ../share/probert/bin/probert
-rwxr-xr-x 1 root root 71928 Jan 18 2018 ptx
-rwxr-xr-x 1 root root 10312 Aug 9 2019 pwdx
-rwxr-xr-x 1 root root 7812 Oct 25 2018 py3clean
-rwxr-xr-x 1 root root 12119 Oct 25 2018 py3compile
lrwxrwxrwx 1 root root 31 Oct 25 2018 py3versions -> ../share/python3/py3versions.py
lrwxrwxrwx 1 root root 8 Oct 25 2018 pydoc3 -> pydoc3.6
-rwxr-xr-x 1 root root 79 Apr 17 20:56 pydoc3.6
lrwxrwxrwx 1 root root 12 Oct 25 2018 pygettext3 -> pygettext3.6
-rwxr-xr-x 1 root root 21547 Apr 17 20:56 pygettext3.6
-rwxr-xr-x 1 root root 372 Sep 25 2017 pyjwt3
lrwxrwxrwx 1 root root 9 Oct 25 2018 python3 -> python3.6
-rwxr-xr-x 2 root root 4526456 Apr 17 20:56 python3.6
-rwxr-xr-x 2 root root 4526456 Apr 17 20:56 python3.6m
-rwxr-xr-x 1 root root 1018 Oct 28 2017 python3-jsondiff
-rwxr-xr-x 1 root root 3661 Oct 28 2017 python3-jsonpatch
-rwxr-xr-x 1 root root 1342 May 1 2016 python3-jsonpointer
-rwxr-xr-x 1 root root 398 Nov 15 2017 python3-jsonschema
lrwxrwxrwx 1 root root 10 Oct 25 2018 python3m -> python3.6m
lrwxrwxrwx 1 root root 3 Jul 7 05:47 rcp -> scp
-rwxr-xr-x 1 root root 26696 May 11 09:40 rdma
-rwxr-xr-x 1 root root 47320 Jan 18 2018 realpath
-rwxr-xr-x 1 root root 14408 Mar 5 11:23 rename.ul
-rwxr-xr-x 1 root root 14408 Mar 5 11:23 renice
lrwxrwxrwx 1 root root 4 May 23 2018 reset -> tset
-rwxr-xr-x 1 root root 38992 Mar 5 11:23 resizepart
-rwxr-xr-x 1 root root 10312 Mar 5 11:23 rev
-rwxr-xr-x 1 root root 30 Jul 11 2017 rgrep
lrwxrwxrwx 1 root root 3 Jul 7 05:47 rlogin -> ssh
-rwxr-xr-x 1 root root 208 May 11 09:40 routef
-rwxr-xr-x 1 root root 1656 May 11 09:40 routel
lrwxrwxrwx 1 root root 3 Jul 7 05:47 rsh -> ssh
lrwxrwxrwx 1 root root 6 May 11 09:40 rtstat -> lnstat
-rwxr-xr-x 1 root root 35000 Jan 18 2018 runcon
-rwxr-xr-x 1 root root 18161 Jul 15 2016 run-mailcap
lrwxrwxrwx 1 root root 8 Jul 7 05:47 rview -> vim.tiny
-rwxr-xr-x 1 root root 10469 Dec 30 2017 savelog
-rwxr-xr-x 1 root root 100496 Mar 4 2019 scp
-rwxr-xr-x 1 root root 30792 Mar 5 11:23 script
-rwxr-xr-x 1 root root 26704 Mar 5 11:23 scriptreplay
-rwxr-xr-x 1 root root 51296 Aug 4 2017 sdiff
lrwxrwxrwx 1 root root 11 Jul 15 2016 see -> run-mailcap
-rwxr-xr-x 1 root root 2442 Mar 12 2018 select-editor
-rwxr-xr-x 1 root root 1209 Mar 12 2018 sensible-browser
-rwxr-xr-x 1 root root 1109 Mar 12 2018 sensible-editor
-rwxr-xr-x 1 root root 433 Mar 12 2018 sensible-pager
-rwxr-xr-x 1 root root 47288 Jan 18 2018 seq
-rwxr-xr-x 1 root root 18784 Mar 5 11:23 setarch
-rwxr-xr-x 1 root root 10312 Mar 5 11:23 setsid
-rwxr-xr-x 1 root root 43088 Mar 5 11:23 setterm
-rwxr-xr-x 1 root root 153960 Mar 4 2019 sftp
lrwxrwxrwx 1 root root 6 Mar 22 2019 sg -> newgrp
-rwxr-xr-x 1 root root 47320 Jan 18 2018 sha1sum
-rwxr-xr-x 1 root root 55512 Jan 18 2018 sha224sum
-rwxr-xr-x 1 root root 55512 Jan 18 2018 sha256sum
-rwxr-xr-x 1 root root 59608 Jan 18 2018 sha384sum
-rwxr-xr-x 1 root root 59608 Jan 18 2018 sha512sum
-rwxr-xr-x 1 root root 59608 Jan 18 2018 shred
-rwxr-xr-x 1 root root 55480 Jan 18 2018 shuf
-rwxr-xr-x 1 root root 26704 Aug 9 2019 skill
-rwxr-xr-x 1 root root 18512 Aug 9 2019 slabtop
lrwxrwxrwx 1 root root 3 Mar 4 2019 slogin -> ssh
lrwxrwxrwx 1 root root 32 Jul 7 05:47 snap -> /snap/snapd/current/usr/bin/snap
lrwxrwxrwx 1 root root 20 Jul 7 05:47 snapctl -> ../lib/snapd/snapctl
lrwxrwxrwx 1 root root 5 Aug 9 2019 snice -> skill
-rwxr-xr-x 1 root root 113120 Jan 18 2018 sort
-rwxr-xr-x 1 root root 55936 Jan 18 2018 split
-rwxr-xr-x 1 root root 727848 Mar 4 2019 ssh
-rwxr-xr-x 1 root root 346248 Mar 4 2019 ssh-add
-rwxr-sr-x 1 root crontab 362640 Mar 4 2019 ssh-agent
-rwxr-xr-x 1 root root 1456 Jan 16 2018 ssh-argv0
-rwxr-xr-x 1 root root 10658 Oct 2 2017 ssh-copy-id
-rwxr-xr-x 1 root root 420000 Mar 4 2019 ssh-keygen
-rwxr-xr-x 1 root root 420000 Mar 4 2019 ssh-keyscan
-rwxr-xr-x 1 root root 80088 Jan 18 2018 stat
-rwxr-xr-x 1 root root 47288 Jan 18 2018 stdbuf
-rwsr-xr-x 1 root root 149080 Jan 31 11:18 sudo
lrwxrwxrwx 1 root root 4 Jan 31 11:18 sudoedit -> sudo
-rwxr-xr-x 1 root root 56128 Jan 31 11:18 sudoreplay
-rwxr-xr-x 1 root root 39104 Jan 18 2018 sum
-rwxr-xr-x 1 root root 1558792 May 3 06:30 systemd-analyze
-rwxr-xr-x 1 root root 10312 May 3 06:30 systemd-cat
-rwxr-xr-x 1 root root 14408 May 3 06:30 systemd-cgls
-rwxr-xr-x 1 root root 30816 May 3 06:30 systemd-cgtop
-rwxr-xr-x 1 root root 22600 May 3 06:30 systemd-delta
-rwxr-xr-x 1 root root 10304 May 3 06:30 systemd-detect-virt
-rwxr-xr-x 1 root root 43104 May 3 06:30 systemd-mount
-rwxr-xr-x 1 root root 10304 May 3 06:30 systemd-path
-rwxr-xr-x 1 root root 88136 May 3 06:30 systemd-resolve
-rwxr-xr-x 1 root root 43080 May 3 06:30 systemd-run
-rwxr-xr-x 1 root root 18504 May 3 06:30 systemd-socket-activate
-rwxr-xr-x 1 root root 14408 May 3 06:30 systemd-stdio-bridge
lrwxrwxrwx 1 root root 13 May 3 06:30 systemd-umount -> systemd-mount
-rwxr-xr-x 1 root root 14328 May 23 2018 tabs
-rwxr-xr-x 1 root root 39096 Jan 18 2018 tac
-rwxr-xr-x 1 root root 67832 Jan 18 2018 tail
-rwxr-xr-x 1 root root 30800 Mar 5 11:23 taskset
-rwxr-xr-x 1 root root 35032 Jan 18 2018 tee
-rwxr-xr-x 1 root root 47288 Jan 18 2018 test
-rwxr-xr-x 1 root root 84080 May 23 2018 tic
-rwxr-xr-x 1 root root 815 Jul 7 05:47 timedatectl
-rwxr-xr-x 1 root root 22600 May 3 06:30 timedatectl.real
-rwxr-xr-x 1 root root 39552 Jan 18 2018 timeout
-rwxr-xr-x 1 root root 14424 Aug 9 2019 tload
-rwxr-xr-x 1 root root 14328 May 23 2018 toe
-rwxr-xr-x 1 root root 108304 Aug 9 2019 top
lrwxrwxrwx 1 root root 10 Jul 6 23:54 touch -> /bin/touch
-rwxr-xr-x 1 root root 18456 May 23 2018 tput
-rwxr-xr-x 1 root root 47288 Jan 18 2018 tr
-rwxr-xr-x 1 root root 39096 Jan 18 2018 truncate
-rwxr-xr-x 1 root root 22528 May 23 2018 tset
-rwxr-xr-x 1 root root 35000 Jan 18 2018 tsort
-rwxr-xr-x 1 root root 30904 Jan 18 2018 tty
-rwxr-xr-x 1 root root 15397 Jun 4 12:25 tzselect
-rwxr-xr-x 1 root root 40685 Feb 25 2018 ucf
-rwxr-xr-x 1 root root 19367 Feb 25 2018 ucfq
-rwxr-xr-x 1 root root 10722 Feb 25 2018 ucfr
-rwxr-xr-x 1 root root 39128 Jan 18 2018 unexpand
-rwxr-xr-x 1 root root 43224 Jan 18 2018 uniq
-rwxr-xr-x 1 root root 30904 Jan 18 2018 unlink
-rwxr-xr-x 1 root root 18712 Mar 5 11:23 unshare
-rwxr-xr-x 1 root root 98008 Jul 5 2018 unsquashfs
-rwxr-xr-x 1 root root 47112 Sep 5 2019 update-alternatives
-rwxr-xr-x 1 root root 10312 Aug 9 2019 uptime
-rwxr-xr-x 1 root root 35000 Jan 18 2018 users
-rwxr-xr-x 1 root root 22600 Mar 5 11:23 utmpdump
-rwxr-xr-x 1 root root 6913 Apr 13 2018 vcs-run
lrwxrwxrwx 1 root root 8 Jul 7 05:47 vi -> vim.tiny
lrwxrwxrwx 1 root root 8 Jul 7 05:47 view -> vim.tiny
-rwxr-xr-x 1 root root 1108024 Mar 18 13:29 vim.tiny
-rwxr-xr-x 1 root root 34912 Aug 9 2019 vmstat
lrwxrwxrwx 1 root root 8 Jul 7 05:47 w -> w.procps
-rwxr-sr-x 1 root tty 30800 Mar 5 11:23 wall
-rwxr-xr-x 1 root root 22952 Aug 9 2019 watch
-rwxr-xr-x 1 root root 43200 Jan 18 2018 wc
-rwxr-xr-x 1 root root 27144 Mar 5 11:23 whereis
lrwxrwxrwx 1 root root 10 Jul 6 23:54 which -> /bin/which
-rwxr-xr-x 1 root root 51416 Jan 18 2018 who
-rwxr-xr-x 1 root root 30904 Jan 18 2018 whoami
-rwxr-xr-x 1 root root 63488 Sep 17 2019 wpa_passphrase
-rwxr-xr-x 1 root root 18504 Aug 9 2019 w.procps
lrwxrwxrwx 1 root root 7 Mar 5 11:23 x86_64 -> setarch
-rwxr-xr-x 1 root root 71896 Nov 5 2017 xargs
-rwxr-xr-x 1 root root 38 Jul 7 05:47 xdg-open
-rwxr-xr-x 1 root root 886 Jul 7 05:47 xdg-settings
-rwxr-xr-x 1 root root 18552 Mar 18 13:29 xxd
-rwxr-xr-x 1 root root 30904 Jan 18 2018 yes
-rwxr-xr-x 1 root root 18488 Jun 4 12:25 zdump
常规命令行窗口的输出片段（从 shell 脚本运行时均缺失）：
lrwxrwxrwx 1 root root 22 Mar 9 10:51 yarn -> ../share/yarn/bin/yarn
lrwxrwxrwx 1 root root 22 Mar 9 10:51 yarnpkg -> ../share/yarn/bin/yarn
-rwxr-xr-x 1 root root 63720 Apr 7 15:15 yelp
-rwxr-xr-x 1 root root 39256 Sep 5 2019 yes
-rwxr-xr-x 1 root root 409 Apr 10 08:47 youtube-dl
lrwxrwxrwx 1 root root 8 Apr 29 12:37 ypdomainname -> hostname