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76 lines
2.0 KiB
Plaintext
76 lines
2.0 KiB
Plaintext
NAME
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fopen - open a file
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SYNOPSIS
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fopen(filename, mode)
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TYPES
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filename string
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mode string
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return file
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DESCRIPTION
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This function opens the file named filename. A file can be
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opened for either reading, writing, or appending. The mode
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is controlled by the mode flag as folllows:
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"r" reading
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"w" writing
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"a" appending
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Names of files are subject to ~ expansion just like the C or
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Korn shell. For example, the file name:
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~/lib/gleet
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refers to the file 'gleet' under the directory lib located
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in your home directory. The file name:
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~chongo/was_here
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refers to the a file 'was_here' under the home directory of
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the user 'chongo'.
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If the open is successful, a value of type 'file' will be returned.
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You can use the 'isfile' function to test the return value to see
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if the open succeeded. You should assign the return value of fopen
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to a variable for later use. File values can be copied to more than
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one variable, and using any of the variables with the same file value
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will produce the same results.
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Standard input, standard output and standard error are always opened
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and cannot be closed.
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The truth value of an opened file is TRUE.
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If the open is unsuccessful, the numeric value of errno is returned.
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You can the errno() builtin to determine what the errno number means.
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EXAMPLE
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> fd = fopen("/etc/motd", "r")
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> print fd
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"/etc/motd"
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> fd
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FILE 3 "/etc/motd" (reading, pos 0)
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> outfile = fopen("~/tmp/output", "w")
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> print outfile
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"~/tmp/output"
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> outfile
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FILE 4 "~/tmp/output" (writing, pos 0)
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> badfile = fopen("not_a_file", "r")
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> if (!isfile(badfile)) print "error #" : badfile : ":", errno(badfile);
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error #2: No such file or directory
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LIMITS
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none
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LIBRARY
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none
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SEE ALSO
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errno, fclose, feof, ferror, fflush, fgetc, fgetline, fgets, files, fopen,
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fprintf, fputc, fputs, fseek, fsize, ftell, isfile, printf, prompt
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