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Talk:Check that file exists: Difference between revisions
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This used <code>chdir()</code> from [[POSIX]] to test a directory. I got compiler error, because [[OpenBSD]] has no <dir.h>; I must use <unistd.h>. I also got "input.txt does exist" when input.txt was a directory, because BSD can <code>fopen()</code> a directory. The current solution for C uses <code>S_ISREG()</code> and <code>S_ISDIR()</code> from POSIX. --[[User:Kernigh|Kernigh]] 00:59, 18 May 2011 (UTC)
==Rename==
I think this should be named "Check if file exists". I think we are checking, rather than ensuring. "Ensure" implies creation if file does not exist. [[User:Markhobley|Markhobley]] 20:13, 18 August 2011 (UTC)
:That seems fine. --[[User:Mwn3d|Mwn3d]] 20:35, 18 August 2011 (UTC)
==Extra credits==
Would it be possible to add a "Extra credits" for the test to make sure that a directory called input.txt is not identified as a file, and vice versa for docs? Or to just add it as a clarification. --Bengt Mon May 27 08:48:26 CEST 2013
== Old solution for GNU Awk ==
<lang AWK>
# syntax: GAWK -f CHECK_THAT_FILE_EXISTS.AWK
BEGIN {
check_exists("input.txt")
check_exists("\\input.txt")
check_exists("docs")
check_exists("\\docs")
exit(0)
}
function check_exists(name, fnr,msg,rec) {
while (getline rec <name > 0) {
fnr++
break
}
# "Permission denied" is for MS-Windows
msg = (ERRNO == 0 || ERRNO ~ /Permission denied/ || fnr > 0) ? "exists" : "does not exist"
printf("%s - %s\n",name,msg)
close(name)
}
</lang>
It reports "not exist" if input.txt is a 0-length file. -- [[User:3havj7t3nps8z8wij3g9|3havj7t3nps8z8wij3g9]] ([[User talk:3havj7t3nps8z8wij3g9|talk]]) 17:34, 23 May 2015 (UTC)
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