Csh prompt windows

The modifiers :e , :h , :t , :r , :q , and :x may be applied to the substitutions above as may :gh , :gt , and :gr. Substitutes 1 if the current input file name is known, 0 if it is not.

Substitutes the decimal process number of the last background process started by this shell. Substitutes a line from the standard input, with no further interpretation. It can be used to read from the keyboard in a shell script.

The remaining substitutions, command and file name substitution, are applied selectively to the arguments of built-in commands. In this case, selectively means that portions of expressions that are not evaluated are not subjected to these expansions. For commands that are not internal to the C Shell, the command name is substituted separately from the argument list.

This occurs very late, after input-output redirection is performed, and in a child of the main shell. The output from such a command is normally broken into separate words at blanks, tabs and newlines, with null words being discarded; this text then replaces the original string. Within double quotes " , only newlines force new words; blanks and tabs are preserved.

In any case, the single final newline does not force a new word. Note that it is thus possible for a command substitution to yield only part of a word, even if the command outputs a complete line. This word is then regarded as a pattern, and replaced with an alphabetically sorted list of file names that match the pattern.

In a list of words specifying file name substitution it is an error for no pattern to match an existing file name, but it is not required for each pattern to match. In matching file names, the character. The character? The sequence Left to right order is preserved, with results of matches being sorted separately at a low level to preserve this order. This construct may be nested. Note: When calling other commands from csh , be careful to escape any wildcards in the command line.

For example, you must type the following in csh :. The standard input and the standard output of a command may be redirected with the following syntax:.

Reads the C Shell input up to a line that is identical to word. Commands that are substituted have all blanks, tabs, and newlines preserved, except for the final newline which is dropped.

The resultant text is placed in an anonymous temporary file that is given to the command as its standard input. Uses filename as the standard output. If the file does not exist then it is created; if the file exists, it is truncated; its previous contents are lost. If the variable noclobber is set, then the file must not exist or be a character special file for example, a terminal or nul or an error results.

This helps prevent accidental destruction of files. Here, the! If the variable noclobber is set, then it is an error for the file not to exist unless one of the! A command receives the environment where the C Shell was invoked as modified by the input-output parameters and the presence of the command in a pipeline. Thus, unlike some previous shells, commands run from a file of C Shell commands have no access to the text of the commands by default; instead they receive the original standard input of the shell.

This permits shell command scripts to function as components of pipelines and allows the shell to block read its input. Note that the default standard input for a command run detached is not modified to be the empty file nul ; instead the standard input remains as the original standard input of the shell.

If this is a terminal and if the process attempts to read from the terminal, then the process blocks and the user is notified see Jobs earlier in this reference page. The standard error output may be directed through a pipe with the standard output. Several of the built-in commands to be described later take expressions, where the operators are similar to those of C, with the same precedence.

These expressions appear in the , exit , if , and while commands. The following operators are available:. Here the precedence increases to the right. Each of the following lines lists operators that have the same level of precedence:. This reduces the need for use of the switch statement in shell scripts when all that is really needed is pattern matching. Strings that begin with 0 are considered octal numbers. Null or missing arguments are considered 0.

The result of all expressions are strings, which represent decimal numbers. The specified name is command and file name expanded and then tested to see if it has the specified relationship to the real user. If the file does not exist or is inaccessible then all enquiries return false, that is, 0. Command executions succeed, returning true, that is, 1 , if the command exits with status 0, otherwise they fail, returning false, that is, 0.

If more detailed status information is required then the command should be executed outside an expression and the variable status examined. The C Shell contains several commands that can be used to regulate the flow of control in command files shell scripts and in limited but useful ways from terminal input.

These commands all operate by forcing the shell to reread or skip in its input and, because of the implementation, restrict the placement of some of the commands. The foreach , switch , and while statements, as well as the if - then - else form of the if statement require that the major keywords appear in a single simple command on an input line as shown later. If the C Shell's input is not seekable, the shell buffers up input whenever a loop is being read and performs seeks in this internal buffer to accomplish the rereading implied by the loop.

To the extent that this allows, a backward goto succeeds on non-seekable inputs. Built-in commands are executed within the C Shell. If a built-in command occurs as any component of a pipeline except the last, it is executed in a subshell. The second form prints the alias for name. The final form assigns the specified wordlist as the alias of name ; wordlist is command and file name substituted. Shows the amount of dynamic memory acquired, broken down into used and free memory.

Causes execution to resume after the end of the nearest enclosing foreach or while. The remaining commands on the current line are executed. Multi-level breaks are thus possible by writing them all on one line. Causes a break from a switch , resuming after the endsw.

Changes the shell's working directory to directory name. If no argument is given then change to the home directory of the user. Continues execution of the nearest enclosing while or foreach. The rest of the commands on the current line are executed.

Labels the default case in a switch statement. The default should come after all case labels. Prints the directory stack; the top of the stack is at the left, the first directory in the stack being the current directory. The specified words are written to the C Shell's standard output, separated by spaces, and terminated with a newline unless the -n option is specified.

See the description of the foreach , if , switch , and while statements later in this reference page. The arguments are read as input to the C Shell and the resulting command s are executed in the context of the current shell. This is usually used to execute commands generated as the result of command or variable substitution, since parsing occurs before these substitutions. The shell exits either with the value of the status variable first form or with the value of the specified expr second form.

The variable name is successively set to each member of wordlist and the sequence of commands between this command and the matching end command are executed. Both foreach and end must appear alone on separate lines. The built-in C Shell command continue may be used to continue the loop prematurely and the built-in C Shell command break may be used to terminate it prematurely. When this command is read from the terminal, the loop is read once prompting with? If you make a mistake typing in a loop at the terminal you can rub it out.

This is useful for programs that want to use the shell to file name expand a list of words. The specified word is file name and command expanded to yield a string of the form label. The shell rewinds its input as much as possible and searches for a line of the form label: possibly preceded by blanks or tabs. Execution continues after the specified line.

Prints a statistics line showing how effective the internal hash table has been at locating commands and avoiding exec s. Displays the history event list; if n is given only the n most recent events are printed. The -r option reverses the order of printout to be most recent first instead of oldest first.

The -h option causes the history list to be printed without leading numbers. This format produces files suitable for sourcing using the -h option to the source command.

If the specified expression evaluates true, then the single command with arguments is executed. Variable substitution on command happens early, at the same time it does for the rest of the if command. If the specified expr is true then the commands up to the first else are executed; otherwise if expr2 is true, the commands up to the second else are executed, and so on. Any number of else - if pairs are possible; only one endif is needed.

The else part is likewise optional. The words else and endif must appear at the beginning of input lines; the if must appear alone on its input line or after an else.

Lists the active jobs; the -l option lists process IDs in addition to the normal information. Sends either the TERM terminate signal or the specified signal to the specified jobs or processes. Signals are either given by number or by names. The signal names are listed by kill -l. Connect and share knowledge within a single location that is structured and easy to search. Inspired by this question , I wanted to try to change my command prompt in this manner. I used setenv because it is the csh equivalent of export and is the closest thing to this procedure , which uses the bash command export.

For csh or tcsh , the environment variable PS1 is meaningless: the prompt is actually configured using a shell variable named prompt. SE and this very well commented example. This might be helpful too. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Needless to say, after creating, editing, printing, and deleting globs of files day after day, someone realized that life would be easier if the shell did the globbing automatically.

And lo, UNIX shells learned to glob. The C shell has this feature of course. Well, not every one. By convention, files that start with a dot are not echoed. Other utilities, like find , use this same convention. The asterisk matches everything except these two characters, and means "zero or more characters.

But each expansion is sorted separately. Within each group, the names would be sorted. Also note that the shell puts all of the files on one line. The echo command can be used as a simple version of the ls command. If the ls command is given the above command, it will sort the filenames again , so they will be in alphabetical order. If you want, you can enable or disable globbing. The command set noglob disables globbing, and unset noglob enables it again. The C shell gives you a choice.

If none of the filename substitutions find a file, you will get an error that says: No match But if you set the "nonomatch" variable: set nonomatch then the C shell behaves like the Bourne Shell.

You should also note that the asterisk can be anywhere in a filename, and you can use any number of asterisks. Therefore echo??? Matching character sets You can match combination of characters, using square brackets.

If any of the characters inside the square brackets match the single character in the filename, the pattern with match. You can also specify a range of characters using a hyphen. If you specify a range in a reverse alphabetical order, the results are unpredictable. Apparently the Bourne shell will treat strange range values as individual characters, while the C shell ignores bogus ranges, except for the starting character.

Combining meta-characters You can combine these meta-characters in any order. Therefore it makes sense to pick filenames that are easy to match with meta-characters. If you had ten chapters in a book, you don't want to name them Part1. Therefore after file "Part1. This can be very useful if you have log files, and use the current date as part of the file name. It is also important to note that the shell evaluates variables before expanding filenames. Then the list of filenames is passed to the echo command.

In-line expansion The C shell has a unique feature, in that it can generate patterns of filenames even if they don't exist. The curly braces are used, and commas separate the pattern.

Suppose you have the file "b0" in the current directory. Also note that "b0" occurs twice. You can put meta-characters inside the curly braces. The Bourne shell does not have this feature. By itself, it expands to the build-in variable "home. C Shell Variable Usage An essential part of understanding the C shell is mastering variables and variable lists.

I always put spaces around the equals sign, as the C shell seems to complain less with extra spaces. How can you check the number of arguments? The C shell has a second way of specifying the arguments passed to the shell script, using a predefined variable list, called "argv" The C shell borrowed this concept from the C programming language.

Wonder why? Hint: it is called the "C" shell for a reason. If the first range is missing, the default is 1, or the first parameter. Variables are allowed inside square brackets. This can be very convenient. Apparently the author of the C shell agreed, because any variable can be an array list. It is the argument list, which is set when the script is called.

You can change this with the "set" command. You must, however, remember to save the current values if you want to use them again. So if you need to manage several arrays, and perhaps use one index to access several arrays, the C shell might make the task easier.

Yes, I realize some consider my statement blasphemous. If you want to give me grief, read my "Curse of the C shell" column three months ago.

I'm not going to sugar coat the C shell beast. It's covered with warts, but it does have some convenient features. Just watch out for the warts. Speaking of which The C shell does not elegantly handle variables that contain spaces. This doesn't work in the C shell. On some versions of SunOS, the variable "b" is empty. On other systems, you get "set: syntax error.

A slight improvement. Some generate an error. Some cause a core dump. Life would be dull without the C shell. The only problem left is spaces inside variables. This, by the way, uses a special for of the "set" command, that can modify a single array element. However, the array must exist first, so the code to copy an array is complicated, and darn ugly too. In general, the C shell is not suited for variables that contain spaces.

I've learned this from my colleges, who've come to the conclusion that anyone who worries about spaces inside arguments is someone who has way too much free time. I don't know anyone like that, however. The command unset a removes the definition of the variable. Testing for variable existence The Bourne shell lets you refer to variables that do not exist. If you ask for the value, you will get an empty string. The C shell will give you a warning if the variable does not exist, or the array element does not exist.

If the variable does not exist, it will have the value of zero. If the variable exists, it will have the value of one. You can combine this with an "if" statement, which is somewhat more cumbersome than the Bourne shell technique.

The Shift command The special command "shift" can be used to remove the first array element. It "pops" the first value of the stack of the argument list.

I've suddenly realized I've been working too hard. I'll continue next month. Until then, take care. C Shell Flow Control We've been talking about variables, lists, and strings. Time to start doing something useful with the C shell. Let's start with a simple way to branch. If any errors occur, the program would exit with a positive value, which typically indicates the error that occurred. If the program "myprogram" generates any output, it will be sent to standard output, which may not be what you want.

It discards it. Putting parenthesis around the "echo" and "cat" commands connects the pipe to the input of both programs. The C shell has some similarities to the Bourne shell. In fact, the above script could be a Bourne shell script. The two shells act the same in this case. However, early versions of the C shell had a bug. This was a long time ago, and I think most versions of the C shell have this bug fixed. Still, it may not be portable. The second difference between the shells is the Bourne shell allows the curly braces to be used as well as the parenthesis.

The parenthesis causes an extra shell to be executed. So the script above requires 4 shells to be executed. The Bourne shell could do it with one shell process.

Still, I find it amusing that the above script works for both the C shell and the Bourne shell. But I don't get out much. The second mechanism for doing tests in the C shell uses the "if" command. There are two formats, a short form and a long form: first the short form if expression command then the long form if expression then command endif The expression is a numerical expression.

If the results is zero, the expression is false. If non-zero, the expression is true. The Bourne shell uses the "test" program to convert numbers and strings into status.

The "if" command does not use status. Assume I created a script, called "myexit," that was simply this:! There is a way to get the exit status inside an expression. It's not a common technique, however. The solution is to enclose the command inside curly braces. Optional forms of the if command The short version of the "if" command without a "then" statement only takes one statement.

You cannot use parenthesis to add additional commands. The following statement generates an error: if 1 echo a;cat an error The "then" word must be included to allow multiple statements. Problems with the if command The C shell has many problems with the "if" command, that the Bourne shell does not have. At first, the C shell seems adequate, but when you try to accomplish something difficult, it may not work.

I've already mentioned: if 1 echo a;cat an error The solution is to use the long form, with the "then" word. Suppose you wanted to optionally empty a file, removing all contents.

The file redirection is started before the command is executed, and before the value of the variable is determined. Therefore the command always empties the file.

The solution is again, to use the long form. You can nest "if" statements inside "if" statements, but combining long and short forms doesn't always work.

Notice a pattern? I personally avoid the short form, because if I add an "else" clause, or a nested "if" statement, I get a syntax error. The next problem is more subtle, but an indication of the ad hoc parsing done by the C shell. The commands that deal with flow control must be the first command on the line. As you recall, the Bourne shell specifies commands have to be on a new line, but a semicolon works as well as a new line.

The C shell requires the command to be the first word. You may have never experienced this problem, but I have. Try to pipe something into a conditional statement. The C shell won't let you do this without creating another script.

The While command The second command used for flow control is the "while This statement will execute the statements inside the loop while the condition is true. I often type the following in a window to examine a print queue: while 1 lpq sleep 10 end This command runs until I press control-C.

As for problems, it's hard to use the C shell to read a file one line at a time. The Foreach command The third command, "foreach," is used to loop through a list. One common use is to loop through the arguments of a script:! It is used as a multiple "if" statement. The test is not an expression, but a string. Here is an example that shows most of these variations.

It prints out the day of the week:! Again, the ad hoc parser is the reason. The "breaksw" command causes the shell to skip to the end. Otherwise, the next statement would be executed. Complex Expressions The Bourne shell uses the program expr to perform arithmetic. It uses the test program to compare the results. The C shell can both calculate complex expressions and test them at the same time.

This provides simplicity, but there are penalties, which I will discuss later. Table 1 shows the list of operators, in order of precedence.

Operators in the same box have the same precedence. The other operators work on numbers. The rest require two numbers or expressions. Null or missing values are considered zero. All results are strings, which may also represent decimal numbers.

Table 2 shows some expressions, and the value after being evaluated. Commands that use expressions Only two flow-control commands support complex expressions, "while," and "if. This allows sophisticated passing of exit codes to a calling program, but I've never seen a C shell script that makes use of this.

Surprisingly, the "set" command does not use complex expressions. A special command, called " " is used. You must have spaces after the " " character. Spaces are almost always required between all operators and expression elements. The C shell likes spaces, and gets grumpy if you don't include enough. A vitamin deficiency, I guess. This construct was taken from the C language. Most of the time the file test operators are used to prevent runtime errors caused by files that are not readable, or executable.

Notice the for command does not support complex expressions. You can emulate the C language for construct using while.

Suppose your script will accept a "-r" option. Then it sees the next operator, which is again a "-r," but in this case there is no filename afterwards. This generates a syntax error. To put it another way, when in doubt, use parenthesis.

The context specifies how parenthesis are used. This is where the parsing of the C shell shows some additional warts. I'm not surprised. Break and continue The C shell has special "escape" commands, used to exit from "while" and "foreach" loops.

The break command will escape out and terminate the loop. The continue command will go to the end of the loop, but cycle through again. Here is a complete shell script that prints out the numbers 2, 4, 6 and 8, but it's nothing to cheer about. Let me know if you have any questions. For those who are keeping score, the Bourne shell is ahead 10 to 2.

Why is the C shell so popular? To explain this requires a short history lesson. Forgive me. When I went to college in the early 70s, programming meant going to the keypunch station and carrying around decks of punch cards.

The first time I used an interactive terminal, directly connected to a computer, it was a hard-copy device. A popular interactive terminal at that time was the Teletype. It had a keyboard, and printed on a ugly roll of yellow paper.

Some models supported a paper tape reader and paper tape punch. It was a bargain, because one machine was a terminal, printer, and backup device. We had a programmer whose job was to edit paper tapes, punching new holes, and splicing paper. The only device used was a Teletype and a tape splicer. If a mistake was made, the "programmer" would position the paper tape just right, and punch out all of the holes to erase that letter.

Each "1" corresponds to a hole, and a row of 8 holes corresponded to a deleted character. If you made a mistake, you could "erase" the mistake without starting a brand new tape. Just back up and punch out the error. We felt fortunate when the boss ordered several video terminals, which cost more than a complete PC system nowadays. Editing was done by the terminal, which had memory, and keys with arrow characters. We were truly excited.

With our new program, that only worked with our new terminal, and 64K of RAM, and 5 MB of hard disk, we now had a real computer system. I imagine Berkeley had computers of a similar configuration, and was equally excited when they got their first VAX.

Trouble was, the default editor, ed , was designed for those old-fashioned hard copy terminals. Ed has a consistent user interface. If you typed something right, it said nothing. If you typed something the program didn't understand, it printed out a single question mark. The authors felt that this was sufficient information, and the interpretation of the error message should be obvious.

Nowadays people comment on this statement as proof that UNIX was not originally user-friendly. You see, Teletypes were incredibly loud. Teletypes were also incredibly slow. I remember pounding on the keys on a model 33 Teletype. Pounding is the right word.

I imagine martial-art students practiced on the keyboard, in their effort attempt to develop strong-as-steel fingers. Alas, I lacked the skill, and the instant I made a mistake, the Teletype let loose a 70 decibel machine-gun rat-a-tat-tat for 5.

When I am irritated, I make mistakes. If the operating systems I used only printed a question mark, the years of electro-shock therapy might not have been necessary. There must be a better way. There was. Bill Joy decided the standard editor sucked, and wrote an editor that did not require special hardware, and allowed you to see what your file looked like while you were editing it.

He wrote a library called termcap to go along with his vi editor. Most people forget what a major breakthrough this was. Going through my edition of the Berkeley UNIX manual, I see that Bill Joy wrote the Pascal interpretor and compiler, along with vmstat , apropos , colcrt , mkstr , strings , whereis , whatis , vgrind , soelim , msgs , and the Pascal modifications to ctags and eyacc.

He also wrote a significant part of the virtual memory, demand paging, and page replacement algorithm for Berkeley Unix. Bill Joy also wrote the C shell.

Twenty years later it's easier to find fault in the C shell, compared with current shells. But at the time, the C shell had many new ideas, and many still favor it for interactive sessions. Several years elapsed before the Korn shell was written. And several more years elapsed before it or similar shells became commonly available. I'd like to meet someone who feels they could have done a better a better job that Bill, in the same conditions. Enough ranting. If you want to capture both standard output and error output, the C shell has a simple syntax.

This also works with pipes. It is true the Bourne shell is more flexible when it comes to file redirection, but the C shell is very easy to understand. The noclobber variable One of the features the C shell has for new users is a special variable that can prevent a user from "shooting oneself in the foot.

Both problems can be prevented very easily. Just set the noclobber variable: set noclobber In the first case, you will get an error that the file already exists. The second will generate an error that there is no such file. This seems like a great idea, but there are times when this feature gets in the way. You may want to write over an existing file. Or you may want to append to a file, but don't know if the file exists or not. If you want to disable this feature, type unset noclobber You may wish to keep this feature enabled, but disable it on a line-by-line basis.

Just add a "! This is like saying "I really mean it! That is, when you want to append to a file that doesn't exist, or write to a file that may exist. A complete list of all of the variations, and their meaning, is below. These options warned the user if a file was going to be destroyed. The C shell supported an alias feature that allows you to define new commands.

If you type alias move mv then when you execute the command "move," the C shell performs a substitution, and executes the "mv" command. The new options, along with the alias command, allowed new users to specify alias mv mv -i alias cp cp -i alias rm rm -i and before any file is destroyed, the system would warn you.

C Shell Start-up Files Since I've started talking about the C shell interactive features, it's time to discuss the start-up files, or files whose name starts with a dot. The shell executes the source command on the file. Find all posts by Corona No luck.

Administrator Emeritus. Join Date: Jun After setting the path i get the same result Code :. The best help I can give you is Don't use C-Shell. This is , not Changing script from csh to bash. Hello Guys I have a script working fine on csh, but I would like to change it to bash, how I should change this command to be able to work as bash script.

Changing the file name to a different one using csh. I have a file name nzdsrndelt1. Changing the shell prompt. Hi, I want to change the shell prompt, using the cd command.

Howto do that? I tried a lot a internet manuals, but it doesn't work.