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shell [2013/09/28 00:59] dblume created |
shell [2018/03/22 10:57] (current) dblume [Command Template] |
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====== shell tips ====== | ====== shell tips ====== | ||
+ | |||
+ | Here's a tutorial: [[http://tldp.org/LDP/abs/html/|Advanced Bash-Scripting Guide]]. | ||
+ | ===== Quick Tips ===== | ||
+ | |||
+ | The [[http://www.reddit.com/r/bashtricks/comments/hdfzc/execute_previous_command_as_root/|History Expansion character]] is "!". To search the history for a previous "scp" command and only print it, try the first line below. But if you want to interactively find that command, type ''<Ctrl>+r,scp''. | ||
+ | |||
+ | <code bash> | ||
+ | $ !?scp?:p | ||
+ | $ ^rscp | ||
+ | </code> | ||
+ | |||
+ | ===== bash expansion ===== | ||
+ | |||
+ | <code bash> | ||
+ | $ cp file{,.bk} | ||
+ | </code> | ||
+ | |||
+ | expands to | ||
+ | |||
+ | <code bash> | ||
+ | $ cp file file.bk | ||
+ | </code> | ||
+ | |||
+ | Replace all files that end with .JPG to .jpeg | ||
+ | |||
+ | <code bash> | ||
+ | for file in *.JPG; do mv $file ${file%.JPG}.jpeg; done | ||
+ | for file in *.JPG; do mv $file ${file/JPG/jpeg}; done | ||
+ | </code> | ||
+ | |||
+ | Then there are two different "rename" commands: | ||
+ | |||
+ | <code bash> | ||
+ | rename .JPG .jpg *.JPG | ||
+ | rename "s/JPG/jpg/" *.JPG | ||
+ | </code> | ||
+ | |||
+ | |||
+ | ===== Command Template ===== | ||
+ | |||
+ | Here's a template for shell commands that demonstrates a number of arguments, length of argument, etc. It could still stand a bit of clean-up according to the [[http://google-styleguide.googlecode.com/svn/trunk/shell.xml|Google Shell Style Guide]]. | ||
+ | |||
+ | Another good resource is [[http://robertmuth.blogspot.com/2012/08/better-bash-scripting-in-15-minutes.html|Better Bash Scripting in 15 minutes]]. | ||
+ | |||
+ | <code bash> | ||
+ | #!/usr/bin/env bash | ||
+ | set -eu -o pipefail # See: https://sipb.mit.edu/doc/safe-shell/ | ||
+ | |||
+ | declare -r SCRIPT_NAME=$(basename "$BASH_SOURCE") | ||
+ | |||
+ | ## exit the shell (default status code: 1) after printing the message to stderr | ||
+ | die() { | ||
+ | echo >&2 "$1" | ||
+ | exit ${2-1} | ||
+ | } | ||
+ | |||
+ | ## the options used by this script | ||
+ | DISK=e | ||
+ | declare -i VERBOSE=0 | ||
+ | |||
+ | ## exit the shell (with status 2) after printing the message | ||
+ | usage() { | ||
+ | echo "\ | ||
+ | $SCRIPT_NAME -hv [Drive Letter] (default: $DISK) | ||
+ | -h Print this help text | ||
+ | -v Enable verbose output | ||
+ | " | ||
+ | exit 2; | ||
+ | } | ||
+ | |||
+ | ## Process the options | ||
+ | while getopts "hv" OPTION | ||
+ | do | ||
+ | case $OPTION in | ||
+ | h) usage;; | ||
+ | v) VERBOSE=1;; | ||
+ | \?) usage;; | ||
+ | esac | ||
+ | done | ||
+ | |||
+ | ## Process the arguments | ||
+ | shift $(($OPTIND - 1)) | ||
+ | |||
+ | if [ $# -eq 0 ]; then | ||
+ | : # Let the default be used | ||
+ | elif [ $# -eq 1 ]; then | ||
+ | if [ ${#1} -eq 1 ]; then | ||
+ | DISK=$1 | ||
+ | else | ||
+ | # 64 is EX_USAGE from sysexits.h | ||
+ | die "$SCRIPT_NAME: Drive Letter can only be one character long." 64 | ||
+ | fi | ||
+ | else | ||
+ | usage; | ||
+ | fi | ||
+ | |||
+ | ## Lock this if only one instance can run at a time | ||
+ | # UNIQUE_BASE=${TMPDIR:-/tmp}/"$SCRIPT_NAME".$$ | ||
+ | LOCK_FILE=${TMPDIR:-/tmp}/"$SCRIPT_NAME"_"$DISK".lock | ||
+ | if [ -f "$LOCK_FILE" ]; then | ||
+ | die "$SCRIPT_NAME is already running. ($LOCK_FILE was found.)" | ||
+ | fi | ||
+ | trap "rm -f $LOCK_FILE" EXIT | ||
+ | touch $LOCK_FILE | ||
+ | |||
+ | ## The main work of this script | ||
+ | |||
+ | if [ ! -d /cygdrive/"$DISK"/backup/Users ]; then | ||
+ | mkdir -p /cygdrive/"$DISK"/backup/Users | ||
+ | fi | ||
+ | |||
+ | ((VERBOSE==1)) && echo "Starting at $(date)" | ||
+ | rsync /cygdrive/c/Users/me /cygdrive/"$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> | ||
+ | |||
+ | ===== Miscellaneous Shell Tips ===== | ||
+ | |||
+ | If you want a single column of just the file and path names, you can get it like so: | ||
+ | |||
+ | <code bash> | ||
+ | ls --format=single-column | ||
+ | </code> | ||
+ | |||
+ | But if you don't know what you're doing, you might construct something like so: | ||
+ | |||
+ | <code bash> | ||
+ | ls -Al | tr -s ' ' | cut -d ' ' -f10- | ||
+ | </code> | ||
+ | |||
+ | - List "almost all" items in "long" format (one line per item) | ||
+ | - Squeeze repeats of the space character | ||
+ | - Cut out everything from before the 10th column and show everything afterwards. | ||
+ | |||
+ | Of course, if you could assert the following: | ||
+ | |||
+ | * none of the first columns were repeats (awk would only identify the first repeated column) | ||
+ | * the desired column didn't have delimiters in it (filenames with spaces) | ||
+ | |||
+ | ...you could use awk | ||
+ | |||
+ | <code bash> | ||
+ | ... | awk '{print $10}' | ||
+ | </code> | ||
+ | |||
+ | Anyway, given a list of directories, they can be inserted into a cp command with xargs if you need. | ||
+ | |||
+ | <code bash> | ||
+ | cat list_of_directories_at_one_level.txt | xargs -I {} cp -r $SOURCEDIRPREFIX:{} $DEST | ||
+ | </code> | ||
Useful bash command for finding strings within python files... | Useful bash command for finding strings within python files... | ||
Line 5: | Line 161: | ||
<code bash> | <code bash> | ||
find . -name \*.py -type f -print0 | xargs -0 grep -nI "timeit" | find . -name \*.py -type f -print0 | xargs -0 grep -nI "timeit" | ||
+ | find . -type f \( -name \*.[ch]pp -or -name \*.[ch] \) -print0 | xargs -0 grep -nI printf | ||
</code> | </code> | ||
Line 93: | Line 250: | ||
<code bash> | <code bash> | ||
seq 1 50 | xargs -I{} -n1 echo '{} Hello World!' | seq 1 50 | xargs -I{} -n1 echo '{} Hello World!' | ||
+ | </code> | ||
+ | |||
+ | When you've set up Perforce to use an application for diff with ''export P4DIFF='vim -d' '', you can still do a regular diff like so: | ||
+ | |||
+ | <code bash> | ||
+ | $ P4DIFF=; p4 diff hello-world.cpp | ||
+ | </code> | ||
+ | |||
+ | It's [[http://stackoverflow.com/questions/47007/determining-the-last-changelist-synced-to-in-perforce|hard to be sure which Perforce changelist you sync'ed if you didn't explicitly sync to a changelist]]. | ||
+ | |||
+ | So, use ''p4_sync'' to sync to a specific changelist, and update a source file too. | ||
+ | |||
+ | <code bash> | ||
+ | p4_sync() { | ||
+ | p4 changes -s submitted -m1 ... | tee p4_sync_to_change.txt | ||
+ | changelist=`cut -d " " -f 2 p4_sync_to_change.txt` | ||
+ | changelist_filename=changelist.h | ||
+ | p4 sync ...@$changelist | ||
+ | if [ -w $changelist_filename ] | ||
+ | then | ||
+ | sed -i 's/"[0-9]\+";/"'$changelist'";/' $changelist_filename | ||
+ | fi | ||
+ | } | ||
+ | </code> | ||
+ | |||
+ | 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> | ||
+ | telnet_log() { | ||
+ | curtime=$(date -Iseconds | tr : .) | ||
+ | args=$(echo "$*" | tr ' ' '_') | ||
+ | telnet $@ | tee $HOME/telnetlog/$args\_${curtime::-5}.log | ||
+ | } | ||
+ | |||
+ | last_telnet_log() { | ||
+ | ls -d1t $HOME/telnetlog/* | head -n 1 | ||
+ | } | ||
+ | </code> | ||
+ | |||
+ | Of course if you do that, you'll want to occasionally (via cronjob?) delete old archives. | ||
+ | |||
+ | <code> | ||
+ | find $HOME/telnetlog/ -type f -mtime +6 -delete | ||
</code> | </code> | ||
Keywords: bash shell sh zsh | Keywords: bash shell sh zsh | ||
+ | |||
+ | ====== .vimrc tips ====== | ||
+ | |||
+ | Here's an alternative way to automatically save backups (with dates in the filename) everytime you save a file. | ||
+ | <code> | ||
+ | set backup | ||
+ | set backupdir=~/.vim/backup/ | ||
+ | au BufWritePre * let &bex = '-' . strftime( "%Y%m%d-%H%M%S" ) | ||
+ | </code> | ||
+ | |||
+ | That makes a lot of files, so you can clean out the backups with a cron job like this: | ||
+ | |||
+ | <code> | ||
+ | # at 3 in the morning on Mondays, delete files older than 30 days | ||
+ | 0 3 * * 1 find $HOME/.vim/backup/ -type f -mtime +30 -delete | ||
+ | </code> | ||
+ | |||
+ | ====== expect tips ====== | ||
+ | |||
+ | What to do when it's not sure you're going to make a connection? | ||
+ | |||
+ | <code> | ||
+ | set times 0 | ||
+ | set made_connection 0 | ||
+ | set timeout 120 | ||
+ | while { $times < 2 && $made_connection == 0 } { | ||
+ | spawn nc $SERVER | ||
+ | send "\r" | ||
+ | expect { | ||
+ | "login:" { | ||
+ | send "john.doe\r" | ||
+ | set made_connection 1 | ||
+ | } eof { | ||
+ | sleep 1s | ||
+ | set times [ expr $times + 1 ] | ||
+ | } timeout { | ||
+ | puts "Didn't expect to timeout." | ||
+ | exit | ||
+ | } | ||
+ | } | ||
+ | } | ||
+ | </code> | ||
+ | |||
+ | I think the following is wrong-headed. It's not usually the case that spawn will fail. | ||
+ | |||
+ | <code> | ||
+ | set times 0; | ||
+ | while { $times < 2 && $made_connection == 0 } { | ||
+ | if { [ catch { spawn nc $SERVER } pid ] } { | ||
+ | set times [ expr $times + 1 ]; | ||
+ | sleep 1s; | ||
+ | } else { | ||
+ | set made_connection 1 | ||
+ | } | ||
+ | } | ||
+ | </code> | ||
+ | |||
+ | ====== Perl tips ====== | ||
+ | |||
+ | 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 | ||
+ | ====== Additional Keywords ====== | ||
+ | |||
+ | Linux, Unix, *nix |