Assignment
The example output in the links above show the results of a program run through a series of tests. The examples show what the PATH environment variable was set to for the test case, the command that was run, the expected results and the output of the program.
PATH ==> /usr/bin:/usr/local/bin:/usr/bin/X11
RAN ==> mar1.sh -a tar
RESULT ==> PASSED
EXPECTED RESULT ==> /usr/bin/tar
PROGRAM OUTPUT ==> /usr/bin/tar
You script will should out put the results (the data after the ==> in the EXPECTED RESULT) section.
Write a shell script to locate executable files. This script takes a list of file names from the command line and determines which would be executed had these names been given as commands.
• The search path should be based only on the user's PATH environment variable. You shall not use the Unix which command, the ksh whence (type) command, the locate command, or the bash type command.
• The code for the script shall not use the UNIX ls command to determine if the file is executable or if it exists.
• The script should find only the first occurrence of the "file". If the file is not found, the script the following
NOT FOUND
would be replaced by the name of the "file" you didn't find.
• If the first parameter is '-a', then the script should print all occurrences of the executable file in the user's path. Again if the file was not on the path, an error message should be displayed.
• The find command shall not be used.
• A project using temporary files will not be graded.
Note:
• The shell variable PATH defines the search path for the directory containing the command. Alternative directory names are separated by a colon (:). The current directory can be specified by two or more adjacent colons, or by a colon at the beginning or end of the path list.
• If the command name contains a / then the search path is not used, you just check if the command/file specified is executable and not a directory. Otherwise, each directory in the path is searched for an executable file.
usage: mywhich [-a] command ....
Examples: The locations of these programs may vary on different systems and the users PATH environment variable.
prompt>mywhich ls
/bin/ls
prompt>mywhich -a cc
/bin/cc
/usr/ucb/cc
prompt>mywhich ./mywhich
./mywhich
prompt>mywhich /bin/ls
/bin/ls
prompt>mywhichfooblar
fooblar not found
prompt>mywhichkshshcsh bash
/usr/bin/ksh
/bin/sh
/bin/csh
/usr/local/bin/bash
The PDF file (in the folder that says Assignment 1 example pdf) has a flow chart example of how to program Assignment 1.
Here is some psuedo code:
BEGIN
set FINDALL to false
IF $1 equals -a THEN
set FINDALL to TRUE
dispose of $1
END-IF
FOR each Positional Parameter ($file) DO
IF $file is a pathname THEN
IF if $file is executable and not a directory THEN
echo $file
ELSE
echo $file is NOT Found
END-IF
ELSE
set FOUND to false
# Don't forget to handle the special cases of PATH
FOR P in PATH (: separated list) DO
IF $P/$file is executable and not a directory THEN
set FOUND to true
echo $P/$file
IF FINDALL is FALSE THEN
BREAK FROMTHE for LOOP
END-IF
ELSE
END-IF
IF FOUND is FALSE THEN
echo $file is NOT FOUND
END-IF
END-FOR
END-IF
END-FOR
END