- |
- Pipe symbol - send the output of one process into another
process. For example, the "ls -l" command prints out
all of the files in the current directory, along with
information about those files, and the "more" command
displays only one screenful of information at a time. If
there are a lot of files in the current directory, you
might want to try "ls -l | more", which makes "ls -l"
send all of it"s output to "more" which then displays
it one screenful at a time. Another useful one is
"ps -ef | grep USERNAME", replacing USERNAME with
the user you"re looking for: it will only show the
lines with that user in them.
- > filename
- Redirect output to a file. This symbol will send the
output of a command to the specified file. For example,
"ls -l > names.dat" will put the names and
permissions of all the files in the local directory into
a file named "names.dat". If you don"t want to see any
output from a command, you can send the output to
"/dev/null" ( "ls -l > /dev/null" would send the
names to "/dev/null", though it doesn"t really serve a
purpose in this example ).
- < filename
- Redirect input from a file. This symbol
will take everything in the file and send it to a process
as if it came from the standard input ( usually the
keyboard ). For example, the "spell" program reads from
standard input and prints out the words that it thinks
are misspelled. So, you can type "spell<RET>",
then type in the words that you want to check followed by
<CTRL>-D ( the end of file mark ), and spell will
print out the misspelled words. If you wanted to check
all of the words in a file, you"d redirect the standard
input to come from the file "spell < filename", and
spell would read the file instead of the keyboard.
- &
- Make a process run in the background automatically. The
process must not need input from the keyboard or output
to the screen. Say the process is "cat file1 file2 >
file3" and the that file1 and file2 are large. This
could take a while before it finishes. To make it run in
the background ( which will allow you to continue to work
while it is running ), the easiest thing to do would be
to use the "&", like so: "cat file1 file2 >
file3 &".
- %#
- Part of the process control available under the csh
shell. "%#" ( where "#" is replaces with a job number
) will re-enter a suspended process. If you use "jobs"
to find the processes that you have suspended or are
running in the background, what you get back might look
like the following:
[1] 21998 Suspended emacs useful.tex
[2] - 22804 Suspended (signal) elm
[3] + 22808 Suspended badb
Where the first number ( in brackets ) is the job
number, and typing "%1" at the command line would cause
you to re-enter the emacs job.
- [CTRL]-c
- Part of the process control available under the csh
shell. <CTRL>-C sends a termination signal to
current process. This usually kills the current process.
- [CTRL]-z
- Part of the process control
available under the csh shell. <CTRL>-Z sends a
terminal stop signal to the current process. This allows
you to temporarily exit a running process, and re-enter
it with "fg". The "jobs" command will show you what
processes you have done this to. If the process doesn"t
require input from the keyboard or output to stdout (
usually the screen ), then after using "<CTRL>-Z"
you can make the process run in the background with
"bg".
- Dvi
{-Pprintername}filename.dvi
- Dvi prints out "filename.dvi" files, which are produced
by the TeX and LaTeX text processing programs. More
information on TeX and LaTeX can be found in the printed
manuals, available for borrowing at the EM computer
facility. "-Pprintername" tells Dvi which printer to
print out on. This parameter isn"t necessary if you"ve
set your "PRINTER" environment variable (do this with
the "setenv" command ).
- Vroff filename
- Vroff is an X-windows previewer for documents that use
the nroff/troff text processing commands. For more
information, look in the document formatting portion of
the printed manuals in room 252 - the "Nroff/Troff
User"s manual" and the "Troff Tutorial" are both worth
looking at.
- Xroff
{-Pprintername}filename
- Xroff prints out documents that use the nroff /troff text
processing commands. For more information, look in the
document formatting portion of the printed manuals in
Votey Hall, Rm. 252 - the "Nroff/Troff User"s manual" and
the "Troff Tutorial" are both worth looking at.
"-Pprintername" specifies which printer to send the
print job to ( i.e. -Pcolorlaz ). This parameter isn"t
necessary if you"ve set your "PRINTER" environment
variable ( do this with the "setenv" command ).
- awk
- Pattern scanning and processing language. Very useful for
making text filters. "awk" can run it"s own script
files ( "awk -f scriptfile inputfile" would run the
script file on the input file ), or it can accept quick
scripts on the command line - "awk "length < 80"
filename" prints to stdout ( usually the screen ) all of
the lines in the file "filename" that are shorter than
80 characters.
- bg
- Background a stopped job. If you start a process that
doesn"t require input from the keyboard or output to the
screen, then you can make it run in the background. Say
the process is "cat file1 file2 > file3" and the
that file1 and file2 are large. This could take a while
before it finishes. If you start the process, and then
realize that you want to make it run in the background (
which will allow you to continue to work while it is
running ), type "<CTRL>-Z" and then "bg". The
process is now backgrounded. You can see the status of
the job with "jobs" or "ps".
- bitmap {filename}
- X-windows bitmap viewer/editor. Bitmaps can be used for
X-window icons and backgrounds. (best if run from SGI
machine, and SUN server (tyr, freyr)
- cedit
- X-windows color viewer. Shows what color a particular
decimal value of RGB looks like. Runs from SGI machines.
- compress
{filename}
- Reduces the size of the named file using adaptive
Lempel-Ziv coding. Whenever possible, each file is
replaced by one with the extension ".Z", while keeping
the same ownership modes. If "filename" isn"t
specified, compress will compress its standard input.
- etags
- Creates a tags file for use with emacs and epoch. A tags
file gives the location of functions and type definitions
in a group of files. Emacs and epoch use entries in the
tags file to locate and display a definition. To go to a
function definition in emacs, type "M-." ( Meta period
). This will ask you the name of the function that you
wish to find. Type it in and press return. If what you
typed in is found at the beginning of a number of
functions, you might not get the correct one on the first
try. If this is the case, keep typing "M-," ( Meta
comma ) until you reach the one that you want.
- fg {%jobnumber}
- Run a currently backgrounded process in the foreground.
If you use "jobs" to find the processes that you have
suspended or running in the background, what you get back
might look like the following:
[1] 21998 Suspended emacs useful.tex
[2] - 22804 Suspended (signal) elm
[3] + 22808 Suspended badb
Simply typing "fg" at the command line will put you
back in the process that has the "+" in the 2nd column,
in this case it would be the "badb" process. "fg %2"
will put you back in the "elm" process.
- grep {string}{-e
expression}{filename(s)}
- Along with egrep and fgrep, grep is used to search files
for a string or a regular expression. If no "filename"
is given, grep searches it"s standard input for the the
string or expression. When grep finds the requested
string or expression, it prints out the line that
contains it along with the filename of the file that the
line is from. Example: "grep chance *" will search all
of the files in the current directory for the word
"chance".
- gtar
- GNU project"s version of "tar". gtar"s command line
parameters are similar to those of tar. gtar has the
added advantage of not trying to keep the original file
ownership of files being extracted. All files are changed
to belong to the person doing the extraction. To create
an archive, you might type "gtar cvf archname file1
file2 file3", which would put file1-3 in the archive
named archname. "c" of "cvf archname" in the command
line means create the named archive, "v" means verbose
- print names of the files and the operation performed on
them, and the "f archname" gives the name of the
archive that you want to do the operations on. "gtar tvf
archname" will print out the names of all of the files
in the archive, "gtar xvf archname" will extract all of
the files from archname, and "gtar xvf archname
filename" will extract only "filename" from the
archive, provided that it is in the archive in the first
place.
- kill -9
{PID}{%job-number}
- Terminates a process with the process id of PID or the
specified job number. See "jobs" and "ps" for
information on how to find PID"s or job numbers. So, if
the PID is 12345, then "kill -9 12345" will kill the
job. If the job number is 5, then "kill -9 %5" will
kill it.
- latex filename.tex
- LaTeX is a text processing language ( a superset of the
TeX language ), and "latex" compiles this language into
a device independent (dvi) representation of the
resulting document. "latex" will report errors and, if
there are none, give you a file named "filename.dvi".
This file can be previewed with "xdvi", and may be
printed out with "Dvi". More information on the LaTeX
language is available in the LaTeX manual which you can
borrow from a CEMS counselor.
- nroff {filename}
- "nroff" and "troff" are text processing languages.
The "nroff" program is an ASCII previewer for
nroff/troff files, showing what the file will look like
when it is printed ( prints to stdout - usually the
screen ). This can be handy for looking at nroff/troff
files that you are writing "nroff filename | more", or
for looking at the manual pages that come along with
software that you get from the Internet "nroff -man
filename | more". "Vroff" is a graphical previewer of
nroff/troff files that will show different fonts and
point sizes ( which the nroff program won"t ).
- nice {command}
- Runs a {command} with low priority so others dont
experience "lagg-time".
- popd
- Removes the top directory from the directory stack,
placing you into the new top directory. Use pushd to
place new directories on the stack. If the stack consists
of the following ( leftmost is the top of the stack ):
"/usr / /usr/local/bin", then you will be in the
"/usr" directory, and typing popd will make the stack
look like this: "/ /usr/local/bin", putting you in the
root directory ( / ).
- pushd {directory}
- Pushes "directory" on to the directory stack, placing
you into that directory. If "directory" isn"t
specified, pushd swaps the two top directories on the
stack, placing you into whichever directory is now on the
top of the stack. Use popd to remove stack entries. If
the directory stack looks like this ( use "dirs" to
print out the current directory stack, and the leftmost
directory is top of stack): "/ /bin", and you type
"pushd /usr/local/bin", then the new stack looks like
this: "/usr/local/bin / /bin", and you will be in the
/usr/local/bin directory. If you then type "pushd", the
stack will look like this: "/ /usr/local/bin /bin" and
you will be in the root directory. Finally if you type
"pushd +2" the stack will look like this: "/bin /
/usr/local/bin", and you will be in the /bin directory.
- sed {-e script}{-f
scriptfile}{filename}
- Stream editor. Useful for making text filters. "sed"
can take its instructions from a file ( -f scriptfile )
or the command line ( -e script ). For example "sed -e
"s/test/testing/g" filename" will replace every instance
of the word "test" with the word "testing" and print
the result to stdout ( usually the screen ).
- sort
{options}{filename}
- Sorts the input lines alphabetically by default,
numerically if given the "-n" command line option.
Without a "filename", sort works on the standard input.
Otherwise it sorts the lines in the file and writes the
sorted output to stdout ( usually the screen ).
- tar
- Creates tape archives, plus adds to, and extracts files
from tape archives. Sometimes has permission problems
when extracting files by maintaining the ownership of the
files in the archive. If you have this problem, try
"gtar". To create an archive, you might type "tar cvf
archname file1 file2 file3", which would put file1-3 in
the archive named archname. "c" of "cvf archname" in
the command line means create the named archive, "v"
means verbose - print names of the files and the
operation performed on them, and the "f archname" gives
the name of the archive that you want to do the
operations on. "tar tvf archname" will print out the
names of all of the files in the archive, "tar xvf
archname" will extract all of the files from archname,
and "tar xvf archname filename" will extract only
"filename" from the archive, provided that it is in the
archive in the first place.
- uncompress
filename.Z
- Uncompresses files that have been compressed with the
"compress" command (which automatically adds the ".Z"
to the end of the filename).
- uudecode filename
- Decodes files that have been encoded with the
"uuencode" command. "uuencode" changes binary files
into ascii files so that they can be easily e-mailed or
posted to the news.
- uuencode {source-file}file-label
- Converts a binary file into an ASCII-encoded
representation that can be sent using mail(1) or posted
to a news-group. If you don"t specify "source-file",
then uuencode takes its input from standard-input.
"uuencode" sends the encoded output to stdout ( usually
the screen ). When decoded using "uudecode" the
resulting file will be named "file-label".
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