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冷日 (冷日)	發表時間：2016/1/13 3:39
Webmaster 註冊日: 2008/2/19 來自: 發表數: 15771	[轉貼]Shell Scripting: Getting Host and User Names Shell Scripting: Getting Host and User Names From Darby Gilbert on Sat, 06 Feb 1999 I am trying to write a batch file that will pick up the computer name for the naming convention. On NT 4.0 computers, it is no problem. Is there a way to write a batch file that will pick up the computer name and/or user name from the computer so that it will use it to name a file that is produced from the batch file? I have been trying all sorts of different things and also searching the web trying to find answers when I came accross your page. Any help would be greatly appreciated. Thank you. Darby Gilbert Under Linux these (simple interpreted text programs) are called shell scripts (they are technically not "batch files" though the concept is the same). To get the current "computer name" use the ' `hostname`' command. To assign that to a shell or environment variable use a command like: `THISHOST=$(hostname)` ... for the short version (in foo.example.org this command returns just "foo"). You can use: `THISHOST=$(hostname -f)` or: `THISHOST=$(hostname --long)` ... to get the "full" or "long" name (the host.domain string). To get information about the current user (the one running the script) we use the 'id' command. Now, if we just use the command with no options it gives us output like: uid=500(jimd) gid=100(users) groups=100(users),10(wheel),11(test),17(staff), 60(web),40(game) (except that it's all on one line). This is informative for interactive use --- but far too ugly for elegant script parsing. So we use options to get just what we want: USERNAME=$(id -un) UID=$(id -u) PRIMARYGROUP=$(id -gn) PRIMARYGID=$(id -g) GROUPLIST=$(id -Gn) GIDLIST=$(id -G) In other words ' `/usr/bin/id`' takes options `-u` (user) `-g` (primary group), `-G` (list of groups) and `-n`(names, not numeric IDs). So you could construct a crude e-mail address for your user by using: MYEMAIL="`id -un`@`hostname -f`" ... here I've used "backticks" (accent characters) which are the more common form of the "command substitution operator." Normally I use the `$()` form which is easier to read and nestable. I use it here only to demonstrate that they are the same (under `bash` and recent Korn shells at any rate). Here's a simple shell script that takes your list of groups and walks through them one at a time: `#!/bin/bash GLIST=$( /usr/bin/id -Gn) set -- $GLIST while [ "$1" ]; do echo $1 shift done` In this case I use a special form of the ' `set`' built-in command: which resets my list of command line arguments to the value specified. I could do that with just: `set $GLIST` ... which sets `$1` to the first string in `$GLIST`and `$2` to the next one, etc. That would be pretty safe in this case (since I've never seen anyone create a group name starting with a dash). However it is better shell scripting practice to use the `set`'s `--` ("dash, dash") option which signifies the end of all options to the ' `set`' command forcing it to consider the rest of the command line items to be "arguments" (rather than options). This is probably a bit confusing if you don't know about the ' `set`' command. Under bash and Korn shell (at least) you can use command like `set -o noclobber` (or `set -C`) to prevent the overwriting of existing files with shell redirection operators and `set -o noglob` ( `set -f`) to disable filename expansion (the conversion by the shell of `*.txt` into a list of files that match that pattern). There are many other features supported by the typical Unix shell (Bourne family). This discussion has focused entirely on Bourne shells. I don't use csh/tcsh much and don't recommend it for scripting (in which I'm in good company; see: Csh Programming Considered Harmful `http://www.faqs.org/faqs/unix-faq/shell/csh-whynot../../index.html` 原文出處：The Answer Guy 38: Shell Scripting: Getting Host and User Names
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冷日 (冷日)	發表時間：2016/1/13 3:44
Webmaster 註冊日: 2008/2/19 來自: 發表數: 15771	[轉貼]Linux Command: List All Users In The System Linux Command: List All Users In The System by Vivek Gite on April 9, 2012 last updatedApril 10, 2012 in Linux I'm a new Linux sys admin and I'm unable to find the command to list all users on my RHEL server. What is the command to list users under Linux operating systems? /etc/passwd file contains one line for each user account, with seven fields delimited by colons. This is a text file. You can easily list users using the cat command as follows: `$ cat /etc/passwd` Sample outputs: root:x:0:0:root:/root:/bin/bash daemon:x:1:1:daemon:/usr/sbin:/bin/sh bin:x:2:2:bin:/bin:/bin/sh sys:x:3:3:sys:/dev:/bin/sh sync:x:4:65534:sync:/bin:/bin/sync games:x:5:60:games:/usr/games:/bin/sh man:x:6:12:man:/var/cache/man:/bin/sh .... .. ... OR use pages as follows to view /etc/passwd file: `$ more /etc/passwd $ less /etc/passwd` Sample outputs: Fig.01: List users using /etc/passwd All fields are separated by a colon (:) symbol. Total seven fields exists. The first field is username. It is used when user logs in. It should be between 1 and 32 characters in length. Task: Linux List Users Command To list only usernames type the following awk command: `$ awk -F':' '{ print $1}' /etc/passwd` Sample outputs: root daemon bin sys sync games man lp mail news .... .. ..hplip vivek bind haldaemon sshd mysql radvd A Note About System and General Users Each user has numerical user ID called UID. It is defined in /etc/passwd file. The UID for each user is automatically selected using /etc/login.defs file when you use useradd command. To see current value, enter: `$ grep "^UID_MIN" /etc/login.defs $ grep UID_MIN /etc/login.defs` Sample outputs: UID_MIN 1000 #SYS_UID_MIN 100 1000 is minimum values for automatic uid selection in useradd command. In other words all normal system users must have UID >= 1000 and only those users are allowed to login into system if shell is bash/csh/tcsh/ksh etc as defined /etc/shells file. Type the following command to list all login users: ## get UID limit ## l=$(grep "^UID_MIN" /etc/login.defs) ## use awk to print if UID >= $UID_LIMIT ## awk -F':' -v "limit=${l##UID_MIN}" '{ if ( $3 >= limit ) print $1}' /etc/passwd To see maximum values for automatic uid selection in useradd command, enter: awk -F':' -v "min=${l##UID_MIN}" -v "max=${l1##UID_MAX}" '{ if ( $3 >= min && $3<= max ) print $0}' /etc/passwd `$ grep "^UID_MAX" /etc/login.defs` Sample outputs: UID_MAX 60000 In other words all normal system users must have UID >= 1000 (MIN) and UID<= 60000 (MAX) and only those users are allowed to login into system if shell is bash/csh/tcsh/ksh etc as defined /etc/shells file. Here is an updated code: ## get mini UID limit ## l=$(grep "^UID_MIN" /etc/login.defs) ## get max UID limit ## l1=$(grep "^UID_MAX" /etc/login.defs) ## use awk to print if UID >= $MIN and UID <= $MAX ## awk -F':' -v "min=${l##UID_MIN}" -v "max=${l1##UID_MAX}" '{ if ( $3 >= min && $3 <= max ) print $0}' /etc/passwd Sample outputs: vivek:x:500:500::/home/vivek:/bin/bash raj:x:501:501::/home/raj:/bin/ksh ash:x:502:502::/home/ash:/bin/zsh jadmin:x:503:503::/home/jadmin:/bin/sh jwww:x:504:504::/htdocs/html:/sbin/nologin wwwcorp:x:505:505::/htdocs/corp:/sbin/nologin wwwint:x:506:506::/htdocs/intranet:/bin/bash scpftp:x:507:507::/htdocs/ftpjail:/bin/bash rsynftp:x:508:508::/htdocs/projets:/bin/bash mirror:x:509:509::/htdocs:/bin/bash jony:x:510:510::/home/jony:/bin/ksh amyk:x:511:511::/home/amyk:/bin/ksh /sbin/nologin is used to politely refuse a login i.e. /sbin/nologin displays a message that an account is not available and exits non-zero. It is intended as a replacement shell field for accounts that have been disabled or you do not want user to login into system using ssh. To filter /sbin/nologin, enter: #!/bin/bash # Name: listusers.bash # Purpose: List all normal user accounts in the system. Tested on RHEL / Debian Linux # Author: Vivek Gite <www.cyberciti.biz>, under GPL v2.0+ # ----------------------------------------------------------------------------------- _l="/etc/login.defs" _p="/etc/passwd" ## get mini UID limit ## l=$(grep "^UID_MIN" $_l) ## get max UID limit ## l1=$(grep "^UID_MAX" $_l) ## use awk to print if UID >= $MIN and UID <= $MAX and shell is not /sbin/nologin ## awk -F':' -v "min=${l##UID_MIN}" -v "max=${l1##UID_MAX}" '{ if ( $3 >= min && $3 <= max && $7 != "/sbin/nologin" ) "$_p" Sample outputs: vivek:x:500:500::/home/vivek:/bin/bash raj:x:501:501::/home/raj:/bin/ksh ash:x:502:502::/home/ash:/bin/zsh jadmin:x:503:503::/home/jadmin:/bin/sh wwwint:x:506:506::/htdocs/intranet:/bin/bash scpftp:x:507:507::/htdocs/ftpjail:/bin/bash rsynftp:x:508:508::/htdocs/projets:/bin/bash mirror:x:509:509::/htdocs:/bin/bash jony:x:510:510::/home/jony:/bin/ksh amyk:x:511:511::/home/amyk:/bin/ksh Finally, this script lists both system and users accounts: #!/bin/bash # Name: listusers.bash # Purpose: List all normal user and system accounts in the system. Tested on RHEL / Debian Linux # Author: Vivek Gite <www.cyberciti.biz>, under GPL v2.0+ # ----------------------------------------------------------------------------------- _l="/etc/login.defs" _p="/etc/passwd" ## get mini UID limit ## l=$(grep "^UID_MIN" $_l) ## get max UID limit ## l1=$(grep "^UID_MAX" $_l) ## use awk to print if UID >= $MIN and UID <= $MAX and shell is not /sbin/nologin ## echo "----------[ Normal User Accounts ]---------------" awk -F':' -v "min=${l##UID_MIN}" -v "max=${l1##UID_MAX}" '{ if ( $3 >= min && $3 <= max && $7 != "/sbin/nologin" ) print $0 }' "$_p" echo "" echo "----------[ System User Accounts ]---------------" awk -F':' -v "min=${l##UID_MIN}" -v "max=${l1##UID_MAX}" '{ if ( !($3 >= min && $3 <= max && $7 != "/sbin/nologin")) print $0 }' "$_p" Sample outputs: ----------[ Normal User Accounts ]--------------- vivek:x:500:500::/home/vivek:/bin/bash raj:x:501:501::/home/raj:/bin/ksh ash:x:502:502::/home/ash:/bin/zsh jadmin:x:503:503::/home/jadmin:/bin/sh wwwint:x:506:506::/htdocs/intranet:/bin/bash scpftp:x:507:507::/htdocs/ftpjail:/bin/bash rsynftp:x:508:508::/htdocs/projets:/bin/bash mirror:x:509:509::/htdocs:/bin/bash jony:x:510:510::/home/jony:/bin/ksh amyk:x:511:511::/home/amyk:/bin/ksh ----------[ System User Accounts ]--------------- root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin gopher:x:13:30:gopher:/var/gopher:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin nobody:x:99:99:Nobody:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin abrt:x:173:173::/etc/abrt:/sbin/nologin haldaemon:x:68:68:HAL daemon:/:/sbin/nologin ntp:x:38:38::/etc/ntp:/sbin/nologin saslauth:x:499:499:"Saslauthd user":/var/empty/saslauth:/sbin/nologin postfix:x:89:89::/var/spool/postfix:/sbin/nologin apache:x:48:48:Apache:/var/www:/sbin/nologin webalizer:x:67:67:Webalizer:/var/www/usage:/sbin/nologin sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin tcpdump:x:72:72::/:/sbin/nologin mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash memcached:x:498:496:Memcached daemon:/var/run/memcached:/sbin/nologin squid:x:23:23::/var/spool/squid:/sbin/nologin rpc:x:32:32:Rpcbind Daemon:/var/cache/rpcbind:/sbin/nologin rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin nfsnobody:x:65534:65534:Anonymous NFS User:/var/lib/nfs:/sbin/nologin 原文出處：Linux Command: List All Users In The System
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