Unix tools: what if a file is named minus something?

How do you execute a file in Unix? I was told #!/bin/sh, but where is this used.?

• I know in perl you just put .pl (filename.pl) at the end of the file you named, and to run the that you just type perl filename.pl. In unix I being told its something like #!/bin/sh? Where does this go? Does this mean I make the file with #!/bin/sh in front of the file names like #!/bin/sh/filename?

• Answer:

  that is accessed with the shell in UNIX. Here is some basic commands: cal This command will print a calendar for a specified month and/or year. To show this month's calendar, enter: cal To show a twelve-month calendar for 2004, enter: cal 2004 To show a calendar for just the month of June, 1970, enter: cal 6 1970 For more detailed information, see the Knowledge Base document In Unix, how can I display a calendar? cat This command outputs the contents of a text file. You can use it to read brief files or to concatenate files together. To append file1 onto the end of file2, enter: cat file1 >> file2 To view the contents of a file named myfile, enter: cat myfile Because cat displays text without pausing, its output may quickly scroll off your screen. Use the less command (described below) or an editor for reading longer text files. For more detailed information, see the Knowledge Base document In Unix, how do I combine several files into a single file? cd This command changes your current directory location. By default, your Unix login session begins in your home directory. To switch to a subdirectory (of the current directory) named myfiles, enter: cd myfiles To switch to a directory named /home/dvader/empire_docs, enter: cd /home/dvader/empire_docs To move to the parent directory of the current directory, enter: cd .. To move to the root directory, enter: cd / To return to your home directory, enter: cd chmod This command changes the permission information associated with a file. Every file (including directories, which Unix treats as files) on a Unix system is stored with records indicating who has permission to read, write, or execute the file, abbreviated as r, w, and x. These permissions are broken down for three categories of user: first, the owner of the file; second, a group with which both the user and the file may be associated; and third, all other users. These categories are abbreviated as u for owner (or user), g for group, and o for other. To allow yourself to execute a file that you own named myfile, enter: chmod u+x myfile To allow anyone who has access to the directory in which myfile is stored to read or execute myfile, enter: chmod o+rx myfile You can view the permission settings of a file using the ls command, described below. Note: Be careful with the chmod command. If you tamper with the directory permissions of your home directory, for example, you could lock yourself out or allow others unrestricted access to your account and its contents. For more detailed information, see the Knowledge Base document In Unix, how do I change the permissions for a file? cp This command copies a file, preserving the original and creating an identical copy. If you already have a file with the new name, cp will overwrite and destroy the duplicate. For this reason, it's safest to always add -i after the cp command, to force the system to ask for your approval before it destroys any files. The general syntax for cp is: cp -i oldfile newfile To copy a file named meeting1 in the directory /home/dvader/notes to your current directory, enter: cp -i /home/dvader/notes/meeting1 . The . (period) indicates the current directory as destination, and the -i ensures that if there is another file named meeting1 in the current directory, you will not overwrite it by accident. To copy a file named oldfile in the current directory to the new name newfile in the mystuff subdirectory of your home directory, enter: cp -i oldfile ~/mystuff/newfile The ~ character (tilde) is interpreted as the path of your home directory. Note: You must have permission to read a file in order to copy it. date The date command displays the current day, date, time, and year. To see this information, enter: date df This command reports file system disk usage, (i.e., the amount of space taken up on mounted file systems). For each mounted file system, df reports the file system device, the number of blocks used, the number of blocks available, and the directory where the file system is mounted. To find out how much disk space is used on each file system, enter the following command: df If the df command is not configured to show blocks in kilobytes by default, you can issue the following command: df -k du This command reports disk usage (i.e., the amount of space taken up by a group of files). The du command descends all subdirectories from the directory in which you enter the command, reporting the size of their contents, and finally reporting a total size for all the files it finds. To find out how much disk space your files take up, switch to your home directory with the cd command, and enter: du The numbers reported are the sizes of the files; on different systems, these sizes will be in units of either 512 byte blocks or kilobytes. To learn which is the case, use the man command, described below. On most systems, du -k will give sizes in kilobytes. find The find command lists all of the files within a directory and its subdirectories that match a set of conditions. This command is most commonly used to find all of the files that have a certain name. To find all of the files named myfile.txt in your current directory and all of its subdirectories, enter: find . -name myfile.txt -print To look in your current directory and its subdirectories for all of the files that end in the extension .txt , enter: find . -name "*.txt" -print In these examples, the . (period) represents your current directory. It can be replaced by the full pathname of another directory to search. For instance, to search for files named myfile.txt in the directory /home/user/myusername and its subdirectories, enter: find /home/user/myusername/ -name myfile.txt -print On some systems, omitting the final / (slash) after the directory name can cause find to fail to return any results. As a shortcut for searching in your home directory, enter: find "$HOME/" -name myfile.txt -print For more detailed information, see the Knowledge Base document In Unix, what is the find command, and how do I use it to search through directories for files? jobs This command reports any programs that you suspended and still have running or waiting in the background (if you had pressed Ctrl-z to suspend an editing session, for example). For a list of suspended jobs, enter: jobs Each job will be listed with a number; to resume a job, enter % (percent sign) followed by the number of the job. To restart job number two, for example, enter: %2 This command is only available in the csh, bash, tcsh, and ksh shells. kill Use this command as a last resort to destroy any jobs or programs that you suspended and are unable to restart. Use the jobs command to see a list of suspended jobs. To kill suspended job number three, for example, enter: kill %3 Now check the jobs command again. If the job has not been cancelled, harsher measures may be necessary. Enter: kill -9 %3 less and more Both less and more display the contents of a file one screen at a time, waiting for you to press the Spacebar between screens. This lets you read text without it scrolling quickly off your screen. The less utility is generally more flexible and powerful than more, but more is available on all Unix systems while less may not be. To read the contents of a file named textfile in the current directory, enter: less textfile The less utility is often used for reading the output of other commands. For example, to read the output of the ls command one screen at a time, enter: ls -la | less In both examples, you could substitute more for less with similar results. To exit either less or more, press q . To exit less after viewing the file, press q . Note: Do not use less or more with executables (binary files), such as output files produced by compilers. Doing so will display garbage and may lock up your terminal. lpr and lp These commands print a file on a printer connected to the computer network. The lpr command is used on BSD systems, and the lp command is used in System V. Both commands may be used on the UITS systems. To print a file named myfile on a printer named lp1 with lpr, enter: lpr -Plp1 myfile To print the same file to the same printer with lp, enter: lp -dlp1 myfile Note: Do not print to a printer whose name or location is unfamiliar to you. For more detailed information, see the Knowledge Base document In Unix, how do I print files and list or remove print jobs? ls This command will list the files stored in a directory. To see a brief, multi-column list of the files in the current directory, enter: ls To also see "dot" files (configuration files that begin with a period, such as .login ), enter: ls -a To see the file permissions, owners, and sizes of all files, enter: ls -la If the listing is long and scrolls off your screen before you can read it, combine ls with the less utility, for example: ls -la | less For more detailed information, see the Knowledge Base document In Unix, how do I list the files in a directory? man This command displays the manual page for a particular command. If you are unsure how to use a command or want to find out all its options, you might want to try using man to view the manual page. For example, to learn more about the ls command, enter: man ls To learn more about man, enter: man man If you are not sure of the exact command name, you can use man with the -k option to help you find the command you need. To see one line summaries of each reference page that contains the keyword you specify, enter: man -k keyword Replace keyword in the above example with the keyword which you want to reference. Also see the Knowledge Base document In Unix, what is the man command, and how do I use it to read manual pages? mkdir This command will make a new subdirectory. To create a subdirectory named mystuff in the current directory, enter: mkdir mystuff To create a subdirectory named morestuff in the existing directory named /tmp, enter: mkdir /tmp/morestuff Note: To make a subdirectory in a particular directory, you must have permission to write to that directory. mv This command will move a file. You can use mv not only to change the directory location of a file, but also to rename files. Unlike the cp command, mv will not preserve the original file. Note: As with the cp command, you should always use -i to make sure you do not overwrite an existing file. To rename a file named oldname in the current directory to the new name newname, enter: mv -i oldname newname To move a file named hw1 from a subdirectory named newhw to another subdirectory named oldhw (both subdirectories of the current directory), enter: mv -i newhw/hw1 oldhw If, in this last operation, you also wanted to give the file a new name, such as firsthw, you would enter: mv -i newhw/hw1 oldhw/firsthw ps The ps command displays information about programs (i.e., processes) that are currently running. Entered without arguments, it lists basic information about interactive processes you own. However, it also has many options for determining what processes to display, as well as the amount of information about each. Like lp and lpr, the options available differ between BSD and System V implementations. For example, to view detailed information about all running processes, in a BSD system, you would use ps with the following arguments: ps -alxww To display similar information in System V, use the arguments: ps -elf For more information about ps refer to the ps man page on your system. Also see the Knowledge Base document In Unix, what do the output fields of the ps command mean? pwd This command reports the current directory path. Enter the command by itself: pwd For more detailed information, see the Knowledge Base document In Unix, how do I determine my current working directory? rm This command will remove (destroy) a file. You should enter this command with the -i option, so that you'll be asked to confirm each file deletion. To remove a file named junk, enter: rm -i junk Note: Using rm will remove a file permanently, so be sure you really want to delete a file before you use rm. To remove a non-empty subdirectory, rm accepts the -r option. On most systems this will prompt you to confirm the removal of each file. This behavior can be prevented by adding the -f option. To remove an entire subdirectory named oldstuff and all of its contents, enter: rm -rf oldstuff Note: Using this command will cause rm to descend into each subdirectory within the specified subdirectory and remove all files without prompting you. Use this command with caution, as it is very easy to accidently delete important files. As a precaution, use the ls command to list the files within the subdirectory you wish to remove. To browse through a subdirectory named oldstuff, enter: ls -R oldstuff | less rmdir This command will remove a subdirectory. To remove a subdirectory named oldstuff, enter: rmdir oldstuff Note: The directory you specify for removal must be empty. To clean it out, switch to the directory and use the ls and rm commands to inspect and delete files. set This command displays or changes various settings and options associated with your Unix session. To see the status of all settings, enter the command without options: set If the output scrolls off your screen, combine set with less: set | less The syntax used for changing settings is different for the various kinds of Unix shells; see the man entries for set and the references listed at the end of this document for more information. vi This command starts the vi text editor. To edit a file named myfile in the current directory, enter: vi myfile The vi editor works fairly differently from other text editors. If you have not used it before, you should probably look at a tutorial, such as the Knowledge Base document How do I use the vi text editor? Another helpful document for getting started with vi is A quick reference list of vi editor commands. The very least you need to know to start using vi is that in order to enter text, you need to switch the program from command mode to insert mode by pressing i . To navigate around the document with the cursor keys, you must switch back to command mode by pressing Esc. To execute any of the following commands, you must switch from command mode to ex mode by pressing : (the colon key): Enter w to save; wq to save and quit; q! to quit without saving. w and who The w and who commands are similar programs that list all users logged into the computer. If you use w, you also get a list of what they are doing. If you use who, you also get the IP numbers or computer names of the terminals they are using. Terminal control characters for C-shell ^h, backspace erase previously typed character ^u erase entire line of input so far typed ^d end-of-input for programs reading from terminal ^s stop printing on terminal ^q continue printing on terminal ^z suspend currently running job; restart with bg or fg DEL, ^c kill currently running program and allow clean-up before exiting ^\ emergency kill of currently running program with no chance of cleanup Also see a list of special characters that should not be used in filenames. Login and authentication login access computer; start interactive session logout disconnect terminal session passwd change local login password; you must set a strong password that is not easily guessed kinit obtain kerberos ticket for connections to other kerberized computers kdestroy destroy kerberos tickets (authorizations) keeptoken request longer lifetime for kerberos ticket so long-running jobs can access AFS files Information date show date and time history list of previously executed commands pine read or send email messages or networks news groups msgs display system messages man show online documentation by program name info online documentation for GNU programs w, who who is on the system and what they are doing whoami who is logged onto this terminal tpo show system stats and top CPU using processes uptime show one line summary of system status finger find out info about a user@system whois look up information in the Stanford Directory File management cat combine files cp copy files ls list files in a directory and their attributes mv change file name or directory location rm remove files ln create another link (name) to a file chmod set file permissions crypt encode/decode a file with a private key gzip, gunzip compress/decompress a file find find files that match specific criteria Display contents of files cat copy files to display device more show text file on display terminal with paging control head show first few lines of a file(s) tail show last few lines of a file; or reverse line order vi full-featured screen editor for modifying text files pico simple screen editor for modifying text files grep display lines that match a pattern lpr send file to line printer pr format file with page headers, multiple columns, etc. diff compare two files and show differences cmp compare two binary files and report if different comm compare two files; show common or unique lines od display binary files as eqivalent octal/hex codes strings show printable text embedded in binary files file examine file(s) and guess type: text, data, program, etc. wc count characters, words, and lines in a file Directories cd change to new directory mkdir create new directory rmdir remove empty directory (remove files first) mv change name of directory pwd show current directory Devices df summarise free space on disk drive du show disk space used by files or directories Special character handling for C-shell (See man cs) * match any characters in a file name ~user shorthand for home directory of user $name substitute value of variable name \ turn off special meaning of character that follows ' in pairs, quote string with special chars, except ! " in pairs, quote string with special chars, except !, $ ` in pairs, substitute output from enclosed command Controlling program execution for C-shell (See man csh) & run job in background DEL, ^c kill job in foreground ^z suspend job in foreground fg restart suspended job in foreground bg run suspended job in background ; delimit commands on same line () group commands on same line ! re-run earlier commands from history list jobs list current jobs ps print process screen kill kill background job or previous process nice run program at lower priority at run program at a later time crontab run program at specified intervals limit see or set resource limits for programs alias create alias name for program (in .login) sh, csh execute command file Controlling program input/output for C-shell (See man csh) | pipe output to input > redirect output to a storage file < redirect input from a storage file >> append redirected output to a storage file tee copy input to both file and next program in pipe script make file record of all terminal activity Email and communication pine process mail with fill-screen menu interface or read USENET news groups vacationsetup configure automatic email responses while you are on vacation msgs read system bulletin board messages mail send/read email; can be run by other programs to send exisiting files via email uuencode, uudecode encode/decode a binary file for transmission via email checkma check specific email addresses to see if they are valid, by contacting remote system(s) finger translate real name to account name for email whois look up email addresses in the Stanford Directory talk interactive communication in real-time rn read USENET news groups Editors and formatting utilities sed programmable text editor for data streams vi full-featured editor for character terminals emacs GNU emacs editor for character terminals xemacs GNU emacs editory for X-Windows terminals pico very simple text editor, same as pine Compose screen fmt fill and break lines to make all same length fold break long lines to specified length X-Window client programs (output to X terminal or server) xterm provide login shell window xauth manipulate authorization files xload show system load xman full screen online manual viewer pinex send or recieve mail messages xemacs GNU emacs editor gv interface to contol gs to display PostScript or PDF files on screen xdvi display DVI files on X-Window (screen preview) netscape web browser gnuplot interactive data plotting on screen TeX typesetting system tex process TeX files to DVI (device independent) output latex process LaTeX files to DVI texpr process and print TeX and LaTeX in one step dvips print DVI files on Postscript laser printer xdvi display DVI files on X-Window (screen preview) latex2html translate LaTeX files to HTML (for web pages) Printing lpr send file to print queue lpq examine status of files in print queue lprm remove a file from print queue op lpc abort qname abort print queue qname to clear printer (all files saved) op lpc start qname restart print queue qname enscript convert text files to PostScript format for printing Interpreted languages and data manipulation utilities sed programmable text editor for data streams awk pattern scanning and processing language; 1985 vers. perl Practical Extraction and Report Language sort sort or merge lines in a file(s) by specified fields tr translate characters cut cut out columns from a file paste paste columns into a file dd copy data between devices; reblock; convert EBCDIC Graphics and mapping gnuplot interactive data plotting; outputs to PostScript or X-windows GMT general 2D and 3D data processing and plotting software package; also plots maps gs "ghostscript" converter displays PostScript files on X-window displays or other devices Networking/communications klogin remote login to kerberized computer; encrypted krsh execute single command on remote kerberized computer; encrypted krcp remote file copy to/from kerberized computer; encrypted ssh remote login/command execution; encrypted scp remote non-interactive file copy; encrypted sftp remote interactive file copy; encrypted telnet remote network login - plain text password ftp network file transfer program - plain text passwords rlogin remote login to "trusted" computer that is not kerberized rsh execute single command on remote "trusted" computer rcp remote file copy to/from "trusted" computer host find IP address for given host name, or vice versa netscape web browser for X-window terminals/servers lynx web browser for character based (text-only) terminals kermit transfer files over modem connections gzip, gunzip compress/decompress a file tar combine multiple files/dirs into single archive uuencode, uudecode encode/decode a binary file for transmission via email Compilers, interpreters and programming tools csh command language interpreter (C-shell scripts) ksh command language interpreter (Korn-shell scripts) sh command language interpreter (Borne-shell scripts) f77 Compaq(HP) Fortran 77 compiler f95 Compaq(HP) Fortran 90/95 compiler f2c convert fortran source code to C source code cc, c89 Compaq(HP) ANSI 89 standard C compiler cxx Compaq(HP) C++ compiler gcc GNU C compiler g++ GNU C++ compiler pc Compaq(HP) Pascal compiler dbx command-line symbolic debugger for compiled C or Fortran ladebug X-window symbolic debugger for compiled C or Fortran make recompile programs from modified source gmake GNU version of make utility cflow generate C flow graph error analyze and disperse compiler error messages Programming libraries (see man library_name) lapack Fortran 77 routines for numerical linear algebra (supersedes LINPACK and EISPACK) X routines to interface with X window system (no man page -- get the X Toolkit book) dbm database routines xdr library routines for external data representation netcdf routines for machine independent data representation Tape manipulation and archiving mt manipulate tape drive and position tape dd unformatted tape read and write; file conversion tar archive disk files on tape or disk ltf read/write ANSI standard label tapes Geology programs supcrt92 thermodynamic properties of high P/T reactions diagram calculate activity phase diagrams from log K values UNIX tutorial: http://www.injunea.demon.co.uk/pages/page203.htm http://cals.arizona.edu/ecat/web/permissions.html http://cals.arizona.edu/ecat/classes/videoclips.html http://www.oreillynet.com/cs/user/view/cs_msg/33720