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How to check if a symlink exists
... the GNU manpage, -h is identical to -L, but according to the BSD manpage, it should not be used:
-h file True if file exists and is a symbolic link. This operator is retained for compatibility with previous versions of this program. Do not rely on its existence; use -L instead.
...
How to trace the path in a Breadth-First Search?
...path
# enumerate all adjacent nodes, construct a new path and push it into the queue
for adjacent in graph.get(node, []):
new_path = list(path)
new_path.append(adjacent)
queue.append(new_path)
print bfs(graph, '1', '11')
Another approach would...
Take the content of a list and append it to another list
I am trying to understand if it makes sense to take the content of a list and append it to another list.
7 Answers
...
Is There a Better Way of Checking Nil or Length == 0 of a String in Ruby?
...rried about performance, I'll often use this:
if my_string.to_s == ''
# It's nil or empty
end
There are various variations, of course...
if my_string.to_s.strip.length == 0
# It's nil, empty, or just whitespace
end
...
Difference between `set`, `setq`, and `setf` in Common Lisp?
...ones. And
there was no SETQ or SETF, just the SET function.
What is now written as:
(setf (symbol-value '*foo*) 42)
was written as:
(set (quote *foo*) 42)
which was eventually abbreviavated to SETQ (SET Quoted):
(setq *foo* 42)
Then lexical variables happened, and SETQ came to be used for ...
An example of how to use getopts in bash
...) { echo "Usage: $0 [-s <45|90>] [-p <string>]" 1>&2; exit 1; }
while getopts ":s:p:" o; do
case "${o}" in
s)
s=${OPTARG}
((s == 45 || s == 90)) || usage
;;
p)
p=${OPTARG}
;;
*)
us...
How do I Search/Find and Replace in a standard string?
Is there a way to replace all occurrences of a substring with another string in std::string ?
9 Answers
...
Are HTTP cookies port specific?
...s "Historic") and formalizes the syntax for real-world usages of cookies. It clearly states:
Introduction
...
For historical reasons, cookies contain a number of security and privacy infelicities. For example, a server can indicate that a given cookie is intended for "secure" c...
An efficient way to transpose a file in Bash
...file >/dev/null
real 0m0.390s
user 0m0.370s
sys 0m0.010s
EDIT by Ed Morton (@ghostdog74 feel free to delete if you disapprove).
Maybe this version with some more explicit variable names will help answer some of the questions below and generally clarify what the script is doing. It a...
JPA and Hibernate - Criteria vs. JPQL or HQL
What are the pros and cons of using Criteria or HQL ? The Criteria API is a nice object-oriented way to express queries in Hibernate, but sometimes Criteria Queries are more difficult to understand/build than HQL.
...