Differences

This shows you the differences between two versions of the page.

Link to this comparison view

shell [2015/08/13 09:35]
dblume [Miscellaneous Shell Tips]
shell [2018/04/24 11:20] (current)
dblume [Sort by Frequency]
Line 45: Line 45:
  
 <code bash> <code bash>
-#!/bin/bash +#!/usr/bin/env bash 
-set -euf -o pipefail # See: https://sipb.mit.edu/doc/safe-shell/+set -eu -o pipefail # See: https://sipb.mit.edu/doc/safe-shell/
  
 declare -r SCRIPT_NAME=$(basename "$BASH_SOURCE") declare -r SCRIPT_NAME=$(basename "$BASH_SOURCE")
Line 113: Line 113:
 ((VERBOSE==1)) && echo "Starting at $(date)" ((VERBOSE==1)) && echo "Starting at $(date)"
 rsync /cygdrive/c/Users/me /cygdrive/"$DISK"/backup/Users rsync /cygdrive/c/Users/me /cygdrive/"$DISK"/backup/Users
 +
 +# We add "|| true" because we don't want to stop 
 +# if the directory was already empty
 +rm -r /cygdrive/c/Users/me/tmp/* || true
 +
 +# Note how we find the number of cores to use
 +make -C build_subdirectory all -j$(grep -c ^processor /proc/cpuinfo)
 </code> </code>
  
Line 268: Line 275:
 </code> </code>
  
-Note the use of $@ vs "$*" in the next function that automatically saves an archive of a telnet session.+Note the use of $@ vs "$*" in the next function that automatically saves an archive of a telnet session. Also note that I remove spaces and colons. (Colons because they screw with opening files directly at line numbers).
  
 <code bash> <code bash>
 telnet_log() { telnet_log() {
-    curtime=$(date -Iseconds)+    curtime=$(date -Iseconds | tr : .)
     args=$(echo "$*" | tr ' ' '_')     args=$(echo "$*" | tr ' ' '_')
     telnet $@ | tee $HOME/telnetlog/$args\_${curtime::-5}.log     telnet $@ | tee $HOME/telnetlog/$args\_${curtime::-5}.log
 +}
 +
 +last_telnet_log() {
 +    ls -d1t $HOME/telnetlog/* | head -n 1
 } }
 </code> </code>
Line 346: Line 357:
 The module ''Search::Dict'' has a "''look''" function that can be used to do a binary search in an ordered dictionary file (a logfile (or log file) that starts with timestamps works). ''File::SortedSeek'' might also be recommended. The module ''Search::Dict'' has a "''look''" function that can be used to do a binary search in an ordered dictionary file (a logfile (or log file) that starts with timestamps works). ''File::SortedSeek'' might also be recommended.
  
 +====== Application Memory Usage ======
 +
 +Use VM Resident Set Size.  See VmRSS below. (Note the [[http://stackoverflow.com/questions/10400751/how-do-vmrss-and-resident-set-size-match|difference between RSS and VmRSS]]. If one process has memory mapped, it's not usable any any other process)
 +
 +<code bash>
 +host:# ps -ef | grep etflix
 +default   1532  1081  6 22:06 ?        00:01:21 pkg_/metflix 
 +root      2108  1046  0 22:26 ?        00:00:00 grep etflix
 +host:# pidof netflix
 +1532
 +host:# cat /proc/1532/status
 +Name:   MAIN
 +...
 +Groups:
 +VmPeak:   220776 kB
 +VmSize:   210096 kB
 +VmLck:         0 kB
 +VmHWM:     95168 kB
 +VmRSS:     74488 kB
 +...
 +</code>
 +
 +Or, while running an application, to see how much is free over time, do this from another shell:
 +<code bash>
 +while [ 1 ]
 +do
 +    free -m | grep Mem
 +    sleep 3
 +done
 +</code>
 +
 +====== Measuring Available Memory ======
 +
 +This note doesn't entirely make sense to me. Maybe need to study up on "cat /proc/meminfo" vs. "cat /proc/vmstat" vs. "vmstat".
 +
 +The best measure I've found for "available memory" is nr_inactive_file_pages+nr_active_file_pages+nr_free_pages from /proc/vmstat. And then you have to subtract out some heuristically determined value which is base system working set. (That heuristically determined value can be 30-40MB.)
 +
 +The command ''free'' just isn't a great indicator in general of how much memory is available because it doesn't account for the cached  file-backed pages that could be dumped to make more memory available.
 +====== Shared Memory Usage ======
 +
 +To increase limit to 256MB from command line:
 +
 +<code bash>
 +echo "268435456" > /proc/sys/kernel/shmmax
 +echo "268435456" > /proc/sys/kernel/shmall
 +</code>
 +
 +Or, edit /etc/sysctl.conf:
 +
 +<code>
 +kernel.shmmax= 268435456
 +kernel.shmall= 268435456
 +</code>
 +
 +====== Performance Metrics ======
 +
 +  * Use [[http://man7.org/linux/man-pages/man1/perf-timechart.1.html|perf-timechart]]
 +  * [[https://github.com/gperftools/gperftools|gperftools]]
 +
 +And you can scrape logs that start with timecodes to create Spreadsheet charts. Given logs like:
 +
 +<code>
 +2016-10-13 19:54:44  memory 22a4
 +</code>
 +
 +On a Macintosh:
 +
 +<code bash>
 +grep memory devicelogs.txt | tr -s ' ' | cut -d " " -f 1,2,4 | \
 +sed 's/\([0-9\-]\+\) \([0-9:]\+\).[0-9]\+ \([0-9a-f]\+\)/\1,\2,=DATEVALUE("\1")+TIMEVALUE("\2"),=HEX2DEC("\3")/' >  heapinfo.csv; \
 +open heapinfo.csv -a "Microsoft Excel"
 +</code>
 +
 +And on Linux, instead of opening Microsoft Excel, that last line would be:
 +
 +<code bash>
 +libreoffice --calc heapinfo.csv
 +</code>
 +
 +====== Cron ======
 +
 +Keep tasks serialized with [[https://linux.die.net/man/1/flock|flock(1)]]:
 +
 +    (
 +         flock -n 9 || exit 1
 +         # ... commands executed under lock ...
 +    ) 9>/var/lock/mylockfile
 +
 +
 +====== Retrieving Symbols with addr2line ======
 +
 +You can gather a backtrace (stacktrace) with this piped command to addr2line.
 +
 +    $ cat << EOF | cut -d " " -f 3 | tr -d "[]" | \
 +      addr2line -e builds/austin/src/platform/gibbon/netflix | \
 +      xargs -d '\n' realpath --relative-to=.
 +    > 7/22 app() [0xf7878] (0xf7878)
 +    > 8/22 app() [0x39c2f8] (0x39c2f8)
 +    > 9/22 app() [0xe1964] (0xe1964)
 +    > EOF
 +    src/Application.h:106 (discriminator 3)
 +    src/platform/main.cpp:521
 +    src/Application.cpp:95
 +    
 +====== Sort by Frequency ======
 +
 +I ran the following P4 command to find out who's been editing a file recently:
 +
 +    $ find . -name fname.cpp | xargs p4 filelog -s -m 10 | grep -P "^\.\.\. #" | \
 +      awk '{print $9}' | cut -d @ -f 1 | sort | uniq -c | sort -nr
 ====== Additional Keywords ====== ====== Additional Keywords ======
  
 Linux, Unix, *nix Linux, Unix, *nix
shell.1439483751.txt.gz · Last modified: 2015/08/13 09:35 by dblume
 
Recent changes RSS feed Driven by DokuWiki