Thank you for the insights, Rolf and Henrik.
To give another example, this time in non-interactive mode,
Rscript -e "file.exists(commandArgs(TRUE))" <(echo "Hi")
[1] TRUE
versus
Rscript -e "normalizePath(commandArgs(TRUE))" <(echo "Hi")
[1] "/dev/fd/63"
Warning message:
In normalizePath(commandArgs(TRUE)) :
path[1]="/dev/fd/63": No such file or directory
It almost seems like file.exists and normalizePath use separate criteria
for determining existence?
Regards
Ben
On 01/12/2017 01:42 AM, Rolf Turner wrote:
On 12/01/17 16:33, Henrik Bengtsson wrote:
<SNIP>
FYI, the /proc is there because Unix has something called the "proc
filesystem (procfs; https://en.wikipedia.org/wiki/Procfs) is a special
filesystem in Unix-like operating systems that presents information
about processes and other system information in a hierarchical
file-like structure". For instance, you can query the uptime of the
machine by reading from /proc/uptime:
$ cat /proc/uptime
332826.96 661438.10
$ cat /proc/uptime
332871.40 661568.50
You can get all IDs (PIDs) of all processes currently running:
$ ls /proc/ | grep -E '^[0-9]+$'
and for each process you there are multiple attributes mapped as
files, e.g. if I start R as:
$ R --args -e "message('hello there')"
then I can query that process as:
$ pid=$(pidof R)
$ echo $pid
26323
$ cat /proc/26323/cmdline
/usr/lib/R/bin/exec/R--args-emessage('hello there')
Unix is neat
Indeed. Couldn't agree more. Thanks for the insight.
<SNIP>
cheers,
Rolf
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