Reading with cat: Stop when not receiving data - linux

Is there any way to tell the cat command to stop reading when not receiving any data? maybe with some "timeout" that specifies for how long no data is incoming.
Any ideas?

There is a timeout(1) command. Example:
timeout 5s cat /dev/random
Dependening on your circumstances. E.g. you run bash with -e and care normally for the exit code.
timeout 5s cat /dev/random || true

cat itself, no. It reads the input stream until told it's the end of the file, blocking for input if necessary.
There's nothing to stop you writing your own cat equivalent which will use select on standard input to timeout if nothing is forthcoming fast enough, and exit under those conditions.
In fact, I once wrote a snail program (because a snail is slower than a cat) which took an extra argument of characters per second to slowly output a file (a).
So snail 10 myprog.c would output myprog.c at ten characters per second. For the life of me, I can't remember why I did this - I suspect I was just mucking about, waiting for some real work to show up.
Since you're having troubles with it, here's a version of dog.c (based on my afore-mentioned snail program) that will do what you want:
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <sys/select.h>
static int dofile (FILE *fin) {
int ch = ~EOF, rc;
fd_set fds;
struct timeval tv;
while (ch != EOF) {
// Set up for fin file, 5 second timeout.
FD_ZERO (&fds); FD_SET (fileno (fin), &fds);
tv.tv_sec = 5; tv.tv_usec = 0;
rc = select (fileno(fin)+1, &fds, NULL, NULL, &tv);
if (rc < 0) {
fprintf (stderr, "*** Error on select (%d)\n", errno);
return 1;
}
if (rc == 0) {
fprintf (stderr, "*** Timeout on select\n");
break;
}
// Data available, so it will not block.
if ((ch = fgetc (fin)) != EOF) putchar (ch);
}
return 0;
}
int main (int argc, char *argv[]) {
int argp, rc;
FILE *fin;
if (argc == 1)
rc = dofile (stdin);
else {
argp = 1;
while (argp < argc) {
if ((fin = fopen (argv[argp], "rb")) == NULL) {
fprintf (stderr, "*** Cannot open input file [%s] (%d)\n",
argv[argp], errno);
return 1;
}
rc = dofile (fin);
fclose (fin);
if (rc != 0)
break;
argp++;
}
}
return rc;
}
Then, you can simply run dog without arguments (so it will use standard input) and, after five seconds with no activity, it will output:
*** Timeout on select
(a) Actually, it was called slowcat but snail is much nicer and I'm not above a bit of minor revisionism if it makes the story sound better :-)

mbuffer, with its -W option, works for me.
I needed to sink stdin to a file, but with an idle timeout:
I did not need to actually concatenate multiple sources (but perhaps there are ways to use mbuffer for this.)
I did not need any of cat's possible output-formatting options.
I did not mind the progress bar that mbuffer brings to the table.
I did need to add -A /bin/false to suppress a warning, based on a suggestion in the linked man page. My invocation for copying stdin to a file with 10 second idle timeout ended up looking like
mbuffer -A /bin/false -W 10 -o ./the-output-file

Here is the code for timeout-cat:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
void timeout(int sig) {
exit(EXIT_FAILURE);
}
int main(int argc, char* argv[]) {
int sec = 0; /* seconds to timeout (0 = no timeout) */
int c;
if (argc > 1) {
sec = atoi(argv[1]);
signal(SIGALRM, timeout);
alarm(sec);
}
while((c = getchar()) != EOF) {
alarm(0);
putchar(c);
alarm(sec);
}
return EXIT_SUCCESS;
}
It does basically the same as paxdiablo's dog.
It works as a cat without an argument - catting the stdin. As a first argument provide timeout seconds.
One limitation (applies to dog as well) - lines are line-buffered, so you have n-seconds to provide a line (not any character) to reset the timeout alarm. This is because of readline.
usage:
instead of potentially endless:
cat < some_input > some_output
you can do compile code above to timeout_cat and:
./timeout_cat 5 < some_input > some_output

Try to consider tail -f --pid
I am assuming that you are reading some file and when the producer is finished (gone?) you stop.
Example that will process /var/log/messages until watcher.sh finishes.
./watcher.sh&
tail -f /var/log/messages --pid $! | ... do something with the output

I faced same issue of cat command blocking while reading on tty port via adb shell but did not find any solution (timeout command was also not working). Below is the final command I used in my python script (running on ubuntu) to make it non-blocking. Hope this will help someone.
bash_command = "adb shell \"echo -en 'ATI0\\r\\n' > /dev/ttyUSB0 && cat /dev/ttyUSB0\" & sleep 1; kill $!"
response = subprocess.check_output(['bash', '-c', bash_command])

Simply cat then kill the cat after 5 sec.
cat xyz & sleep 5; kill $!
Get the cat output as a reply after 5 seconds
reply="`cat xyz & sleep 5; kill $!`"
echo "reply=$reply"

Related

Processing backspace control character (^H) in real time while logging sdout to file

I am working on a script to test new-to-me hard drives in the background (so I can close the terminal window) and log the outputs. My problem is in getting badblocks to print stdout to the log file so I can monitor its multi-day progress and create properly formatted update emails.
I have been able to print stdout to a log file with the following: (flags are r/w, % monitor, verbose)
sudo badblocks -b 4096 -wsv /dev/sdx 2>&1 | tee sdx.log
Normally the output would look like:
Testing with pattern 0xaa: 2.23% done, 7:00 elapsed. (0/0/0 errors)
No new-line character is used, the ^H control command backs up the cursor, and then the new updated status overwrites the previous status.
Unfortunately, the control character is not processed but saved as a character in the file, producing the above output followed by 43 copies of ^H, the new updated stats, 43 copies of ^H, etc.
Since the output is updated at least once per second, this produces a much larger file than necessary, and makes it difficult to retrieve the current status.
While working in terminal, the solution cat sdx.log && echo"" prints the expected/wanted results by parsing the control characters (and then inserting a carriage return so it is not immediately printed over by the next terminal line), but using cat sdx.log > some.file or cat sdx.log | mail both still include all of the extra characters (though in email they are interpreted as spaces). This solution (or ones like it which decode or remove the control character at the time of access still produce a huge, unnecessary output file.
I have worked my way through the following similar questions, but none have produced (at least that I can figure out) a solution which works in real time with the output to update the file, instead requiring that the saved log file be processed separately after the task has finished writing, or that the log file not be written until the process is done, both of which defeat the stated goal of monitoring progress.
Bash - process backspace control character when redirecting output to file
How to "apply" backspace characters within a text file (ideally in vim)
Thank you!
The main place I've run into this in real life is trying to process man pages. In the past, I've always used a simple script that post processes by stripping out the backspace appropriately. One could probably do this sort of thing in 80 character of perl, but here's an approach that handles backspace and cr/nl fairly well. I've not tested extensively, but it produces good output for simple cases. eg:
$ printf 'xxx\rabclx\bo\rhel\nworld\n' | ./a.out output
hello
world
$ cat output
hello
world
$ xxd output
00000000: 6865 6c6c 6f0a 776f 726c 640a hello.world.
If your output starts to have a lot of csi sequences, this approach just isn't worth the trouble. cat will produce nice human consumable output for those cases.
#include <assert.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
FILE * xfopen(const char *path, const char *mode);
off_t xftello(FILE *stream, const char *name);
void xfseeko(FILE *stream, off_t offset, int whence, const char *name);
int
main(int argc, char **argv)
{
const char *mode = "w";
char *name = strchr(argv[0], '/');
off_t last = 0, max = 0, curr = 0;
name = name ? name + 1 : argv[0];
if( argc > 1 && ! strcmp(argv[1], "-a")) {
argv += 1;
argc -= 1;
mode = "a";
}
if( argc > 1 && ! strcmp(argv[1], "-h")) {
printf("usage: %s [-a] [-h] file [ file ...]\n", name);
return EXIT_SUCCESS;
}
if( argc < 2 ) {
fprintf(stderr, "Missing output file. -h for usage\n");
return EXIT_FAILURE;
}
assert( argc > 1 );
argc -= 1;
argv += 1;
FILE *ofp[argc];
for( int i = 0; i < argc; i++ ) {
ofp[i] = xfopen(argv[i], mode);
}
int c;
while( ( c = fgetc(stdin) ) != EOF ) {
fputc(c, stdout);
for( int i = 0; i < argc; i++ ) {
if( c == '\b' ) {
xfseeko(ofp[i], -1, SEEK_CUR, argv[i]);
} else if( isprint(c) ) {
fputc(c, ofp[i]);
} else if( c == '\n' ) {
xfseeko(ofp[i], max, SEEK_SET, argv[i]);
fputc(c, ofp[i]);
last = curr + 1;
} else if( c == '\r' ) {
xfseeko(ofp[i], last, SEEK_SET, argv[i]);
}
}
curr = xftello(ofp[0], argv[0]);
if( curr > max ) {
max = curr;
}
}
return 0;
}
off_t
xftello(FILE *stream, const char *name)
{
off_t r = ftello(stream);
if( r == -1 ) {
perror(name);
exit(EXIT_FAILURE);
}
return r;
}
void
xfseeko(FILE *stream, off_t offset, int whence, const char *name)
{
if( fseeko(stream, offset, whence) ) {
perror(name);
exit(EXIT_FAILURE);
}
}
FILE *
xfopen(const char *path, const char *mode)
{
FILE *fp = fopen(path, mode);
if( fp == NULL ) {
perror(path);
exit(EXIT_FAILURE);
}
return fp;
}
You can delete the ^H
sudo badblocks -b 4096 -wsv /dev/sdx 2>&1 | tr -d '\b' | tee sdx.log
I have found col -b and colcrt usefull, but none worked perfect for me. These will apply control characters, not just drop them:
sudo badblocks -b 4096 -wsv /dev/sdx 2>&1 | col -b | tee sdx.log

How to use linux wc command with char array?

Hi~ I'm just making sample program which implements pipe command.
In this program, I'm trying to implement "cat somefile.txt | wc" command..
So I called fork() twice, I used first child process for sending results of "cat somefile.txt" to fd[1].
After that second child process gets the result from fd[0] to text array. (I confirmed it successfully reads and stores datas to text array)
So lastly, what I have to do is to call execl function running wc command with text array as arguments. But as you know, wc needs filename. Of course the final output is not what I wanted.. So I'm in trouble now.
I searched execl , wc but I couldn't find any infos which says wc command can be used with char array.
Do you have any ideas to solve this?
Here's code..
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char text[80];
int main(int argc,char * argv[]){
int fd[2];
if(pipe(fd) == -1){
perror(argv[0]);
exit(1);
}
if(fork() == 0){ // execute cat somefile.txt
dup2(fd[1],1);
close(fd[0]); close(fd[1]);
execl("/bin/cat","cat","somefile.txt",(char *)0);
exit(127);
}
if(fork() == 0){ // execute wc and get datas from cat somefile.txt
dup2(fd[0],0);
close(fd[0]); close(fd[1]);
read_to_nl(text); // I defined but didn't post it. Anyway I confirmed it successfully get results from fd[0] to text array
execl("/usr/bin/wc","wc",text,(char *)0); // how to set arguments to complete command "cat somefile.txt | wc"?
exit(127);
}
close(fd[0]); close(fd[1]);
while(wait((int *) 0) != -1);
return 0;
}

Get the content on the command line with an external promgram

I would like to write a small program which will analyize my current input on the command line and generate some suggesstions like those search engines do.
The problems is how can an external program get the content on command line? For example
# an external program started and got passed in the PID of the shell below.
# the user typed something in the shell like this...
<PROMPT> $ echo "grab this command"
# the external program now get 'echo "grab this command"'
# and ideally the this could be done in realtime.
More over, can I just modify the content of current command line?
EDIT
bash uses libreadline to manage the command line, but still I can not imagine how to make use of this.
You could write your own shell wrapper using c. Open bash in a process using popen and use fgetc and fputc to write the data to the process and the output file.
A quick dirty hack could look like this (bash isn't started in interactive mode, but otherwise should work fine. --> no prompt):
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
pid_t pid;
void kill_ch(int sig) {
kill(pid, SIGKILL);
}
/**
*
*/
int main(int argc, char** argv) {
int b;
FILE *cmd = NULL;
FILE *log = NULL;
signal(SIGALRM, (void (*)(int))kill_ch);
cmd = popen("/bin/bash -s", "r+");
if (cmd == NULL) {
fprintf(stderr, "Error: Failed to open process");
return EXIT_FAILURE;
}
setvbuf(cmd, NULL, _IOLBF, 0);
log = fopen("out.txt", "a");
if (log == NULL) {
fprintf(stderr, "Error: Failed to open logfile");
return EXIT_FAILURE;
}
setvbuf(log, NULL, _IONBF, 0);
pid = fork();
if (pid != 0)
goto EXEC_WRITE;
else
goto EXEC_READ;
EXEC_READ:
while (1) {
b = fgetc(stdin);
if (b != EOF) {
fputc((char) b, cmd);
fputc((char) b, log);
}
}
EXEC_WRITE:
while (1) {
b = fgetc(cmd);
if (b == EOF) {
return EXIT_SUCCESS;
}
fputc(b, stdout);
fputc(b, log);
}
return EXIT_SUCCESS;
}
I might not fully understand your question but I think you'd basically have two options.
The first option would be to explicitly call your "magic" program by prefixing your call with it like so
<PROMPT> $ magic echo "grab this command"
(magic analyzes $* and says...)
Your input would print "grab this command" to stdout
<PROMPT> $
In this case the arguments to "magic" would be handled as positional parameters ($*, $1 ...)
The second option would be to wrap an interpreter-like something around your typing. E.g. the Python interpreter does so if called without arguments. You start the interpreter, which will basically read anything you type (stdin) in an endless loop, interpret it, and produce some output (typically on stdout).
<PROMPT> $ magic
<MAGIC_PROMPT> $ echo "grab this command"
(your magic interpreter processes the input and says...)
Your input would print "grab this command" to stdout
<MAGIC_PROMPT> $

how to define script interpreter with shebang

It is clear that one can use the
#!/usr/bin/perl
shebang notation in the very first line of a script to define the interpreter. However, this presupposes an interpreter that ignores hashmark-starting lines as comments. How can one use an interpreter that does not have this feature?
With a wrapper that removes the first line and calls the real interpreter with the remainder of the file. It could look like this:
#!/bin/sh
# set your "real" interpreter here, or use cat for debugging
REALINTERP="cat"
tail -n +2 $1 | $REALINTERP
Other than that: In some cases ignoring the error message about that first line could be an option.
Last resort: code support for the comment char of your interpreter into the kernel.
I think the first line is interpreted by the operating system.
The interpreter will be started and the name of the script is handed down to the script as its first parameter.
The following script 'first.myint' calls the interpreter 'myinterpreter' which is the executable from the C program below.
#!/usr/local/bin/myinterpreter
% 1 #########
2 xxxxxxxxxxx
333
444
% the last comment
The sketch of the personal interpreter:
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define BUFFERSIZE 256 /* input buffer size */
int
main ( int argc, char *argv[] )
{
char comment_leader = '%'; /* define the coment leader */
char *line = NULL;
size_t len = 0;
ssize_t read;
// char buffer[BUFFERSIZE];
// argv[0] : the name of this executable
// argv[1] : the name the script calling this executable via shebang
FILE *input; /* input-file pointer */
char *input_file_name = argv[1]; /* the script name */
input = fopen( input_file_name, "r" );
if ( input == NULL ) {
fprintf ( stderr, "couldn't open file '%s'; %s\n",
input_file_name, strerror(errno) );
exit (EXIT_FAILURE);
}
while ((read = getline(&line, &len, input)) != -1) {
if ( line[0] != comment_leader ) {
printf( "%s", line ); /* print line as a test */
}
else {
printf ( "Skipped a comment!\n" );
}
}
free(line);
if( fclose(input) == EOF ) { /* close input file */
fprintf ( stderr, "couldn't close file '%s'; %s\n",
input_file_name, strerror(errno) );
exit (EXIT_FAILURE);
}
return EXIT_SUCCESS;
} /* ---------- end of function main ---------- */
Now call the script (made executable before) and see the output:
...~> ./first.myint
#!/usr/local/bin/myinterpreter
Skipped a comment!
2 xxxxxxxxxxx
333
444
Skipped a comment!
I made it work. I especially thank holgero for his tail opion trick
tail -n +2 $1 | $REALINTERP
That, and finding this answer on Stack overflow made it possible:
How to compile a linux shell script to be a standalone executable *binary* (i.e. not just e.g. chmod 755)?
"The solution that fully meets my needs would be SHC - a free tool"
SHC is a shell to C translator, see here:
http://www.datsi.fi.upm.es/~frosal/
So I wrote polyscript.sh:
$ cat polyscript.sh
#!/bin/bash
tail -n +2 $1 | poly
I compiled this with shc and in turn with gcc:
$ shc-3.8.9/shc -f polyscript.sh
$ gcc -Wall polyscript.sh.x.c -o polyscript
Now, I was able to create a first script written in ML:
$ cat smlscript
#!/home/gergoe/projects/shebang/polyscript $0
print "Hello World!"
and, I was able to run it:
$ chmod u+x smlscript
$ ./smlscript
Poly/ML 5.4.1 Release
> > # Hello World!val it = (): unit
Poly does not have an option to suppress compiler output, but that's not an issue here. It might be interesting to write polyscript directly in C as fgm suggested, but probably that wouldn't make it faster.
So, this is how simple it is. I welcome any comments.

Is there a good way to detect a stale NFS mount

I have a procedure I want to initiate only if several tests complete successfully.
One test I need is that all of my NFS mounts are alive and well.
Can I do better than the brute force approach:
mount | sed -n "s/^.* on \(.*\) type nfs .*$/\1/p" |
while read mount_point ; do
timeout 10 ls $mount_point >& /dev/null || echo "stale $mount_point" ;
done
Here timeout is a utility that will run the command in the background, and will kill it after a given time, if no SIGCHLD was caught prior to the time limit, returning success/fail in the obvious way.
In English: Parse the output of mount, check (bounded by a timeout) every NFS mount point. Optionally (not in the code above) breaking on the first stale mount.
A colleague of mine ran into your script. This doesn't avoid a "brute force" approach, but if I may in Bash:
while read _ _ mount _; do
read -t1 < <(stat -t "$mount") || echo "$mount timeout";
done < <(mount -t nfs)
mount can list NFS mounts directly. read -t (a shell builtin) can time out a command. stat -t (terse output) still hangs like an ls*. ls yields unnecessary output, risks false positives on huge/slow directory listings, and requires permissions to access - which would also trigger a false positive if it doesn't have them.
while read _ _ mount _; do
read -t1 < <(stat -t "$mount") || lsof -b 2>/dev/null|grep "$mount";
done < <(mount -t nfs)
We're using it with lsof -b (non-blocking, so it won't hang too) in order to determine the source of the hangs.
Thanks for the pointer!
test -d (a shell builtin) would work instead of stat (a standard external) as well, but read -t returns success only if it doesn't time out and reads a line of input. Since test -d doesn't use stdout, a (( $? > 128 )) errorlevel check on it would be necessary - not worth the legibility hit, IMO.
Took me some time, but here is what I found which works in Python:
import signal, os, subprocess
class Alarm(Exception):
pass
def alarm_handler(signum, frame):
raise Alarm
pathToNFSMount = '/mnt/server1/' # or you can implement some function
# to find all the mounts...
signal.signal(signal.SIGALRM, alarm_handler)
signal.alarm(3) # 3 seconds
try:
proc = subprocess.call('stat '+pathToNFSMount, shell=True, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
stdoutdata, stderrdata = proc.communicate()
signal.alarm(0) # reset the alarm
except Alarm:
print "Oops, taking too long!"
Remarks:
credit to the answer here.
You could also use alternative scheme:
os.fork() and os.stat()
check if the fork finished, if it has timed out you can kill it. You will need to work with time.time() and so on.
In addition to previous answers, which hangs under some circumstances, this snippet checks all suitable mounts, kills with signal KILL, and is tested with CIFS too:
grep -v tracefs /proc/mounts | cut -d' ' -f2 | \
while read m; do \
timeout --signal=KILL 1 ls -d $m > /dev/null || echo "$m"; \
done
You could write a C program and check for ESTALE.
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <iso646.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
int main(){
struct stat st;
int ret;
ret = stat("/mnt/some_stale", &st);
if(ret == -1 and errno == ESTALE){
printf("/mnt/some_stale is stale\n");
return EXIT_SUCCESS;
} else {
return EXIT_FAILURE;
}
}
Writing a C program that checks for ESTALE is a good option if you don't mind waiting for the command to finish because of the stale file system. If you want to implement a "timeout" option the best way I've found to implement it (in a C program) is to fork a child process that tries to open the file. You then check if the child process has finished reading a file successfully in the filesystem within an allocated amount of time.
Here is a small proof of concept C program to do this:
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/wait.h>
void readFile();
void waitForChild(int pid);
int main(int argc, char *argv[])
{
int pid;
pid = fork();
if(pid == 0) {
// Child process.
readFile();
}
else if(pid > 0) {
// Parent process.
waitForChild(pid);
}
else {
// Error
perror("Fork");
exit(1);
}
return 0;
}
void waitForChild(int child_pid)
{
int timeout = 2; // 2 seconds timeout.
int status;
int pid;
while(timeout != 0) {
pid = waitpid(child_pid, &status, WNOHANG);
if(pid == 0) {
// Still waiting for a child.
sleep(1);
timeout--;
}
else if(pid == -1) {
// Error
perror("waitpid()");
exit(1);
}
else {
// The child exited.
if(WIFEXITED(status)) {
// Child was able to call exit().
if(WEXITSTATUS(status) == 0) {
printf("File read successfully!\n");
return;
}
}
printf("File NOT read successfully.\n");
return;
}
}
// The child did not finish and the timeout was hit.
kill(child_pid, 9);
printf("Timeout reading the file!\n");
}
void readFile()
{
int fd;
fd = open("/path/to/a/file", O_RDWR);
if(fd == -1) {
// Error
perror("open()");
exit(1);
}
else {
close(fd);
exit(0);
}
}
I wrote https://github.com/acdha/mountstatus which uses an approach similar to what UndeadKernel mentioned, which I've found to be the most robust approach: it's a daemon which periodically scans all mounted filesystems by forking a child process which attempts to list the top-level directory and SIGKILL it if it fails to respond in a certain timeout, with both successes and failures recorded to syslog. That avoids issues with certain client implementations (e.g older Linux) which never trigger timeouts for certain classes of error, NFS servers which are partially responsive but e.g. won't respond to actual calls like listdir, etc.
I don't publish them but the included Makefile uses fpm to build rpm and deb packages with an Upstart script.
Another way, using shell script. Works good for me:
#!/bin/bash
# Purpose:
# Detect Stale File handle and remove it
# Script created: July 29, 2015 by Birgit Ducarroz
# Last modification: --
#
# Detect Stale file handle and write output into a variable and then into a file
mounts=`df 2>&1 | grep 'Stale file handle' |awk '{print ""$2"" }' > NFS_stales.txt`
# Remove : ‘ and ’ characters from the output
sed -r -i 's/://' NFS_stales.txt && sed -r -i 's/‘//' NFS_stales.txt && sed -r -i 's/’//' NFS_stales.txt
# Not used: replace space by a new line
# stales=`cat NFS_stales.txt && sed -r -i ':a;N;$!ba;s/ /\n /g' NFS_stales.txt`
# read NFS_stales.txt output file line by line then unmount stale by stale.
# IFS='' (or IFS=) prevents leading/trailing whitespace from being trimmed.
# -r prevents backslash escapes from being interpreted.
# || [[ -n $line ]] prevents the last line from being ignored if it doesn't end with a \n (since read returns a non-zero exit code when it encounters EOF).
while IFS='' read -r line || [[ -n "$line" ]]; do
echo "Unmounting due to NFS Stale file handle: $line"
umount -fl $line
done < "NFS_stales.txt"
#EOF
I'll just paste a snippet from our Icinga2 NFS stale mount monitoring Bash script here:
MOUNTS="$(mount -t nfs;mount -t nfs3;mount -t nfs4)"
MOUNT_POINTS=$(echo -e "$MOUNTS \n"|grep -v ^$|awk '{print $3}')
if [ -z "$MOUNT_POINTS" ]; then
OUTPUT="[OK] No nfs mounts"
set_result 0
else
for i in $MOUNT_POINTS;do
timeout 1 stat -t "$i" > /dev/null
TMP_RESULT=$?
set_result $TMP_RESULT
set_output $TMP_RESULT "$i"
done
fi

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