Commands using strace (25)

  • intercept stdout/stderr of another process


    59
    strace -ff -e trace=write -e write=1,2 -p SOME_PID
    oernii2 · 2010-04-20 08:55:54 11
  • List files accessed by a command

    Can be run as a script `ftrace` if my_command is substrituted with "$@" It is useful when running a command that fails and you have the feeling it is accessing a file you are not aware of. Show Sample Output


    17
    strace -ff -e trace=file my_command 2>&1 | perl -ne 's/^[^"]+"(([^\\"]|\\[\\"nt])*)".*/$1/ && print'
    unixmonkey8046 · 2011-08-16 15:00:18 9
  • intercept stdout/stderr of another process

    similar to the previous command, but with more friendly output (tested on linux)


    10
    strace -ff -e write=1,2 -s 1024 -p PID 2>&1 | grep "^ |" | cut -c11-60 | sed -e 's/ //g' | xxd -r -p
    systemj · 2010-04-23 16:22:17 4
  • Determine what an process is actually doing


    7
    sudo strace -pXXXX -e trace=file
    tolginho · 2009-12-01 15:27:48 6
  • See why a program can't seem to access a file

    Sometimes a program refuses to read a file and you're not sure why. You may have display_errors turned off for PHP or something. In this example, fopen('/var/www/test/foo.txt') was called but doesn't have read access to foo.txt. Strace can tell you what went wrong. E.g., if php doesn't have read access to the file, strace will say "EACCESS (Permission denied)". Or, if the file path you gave doesn't exist, strace will say "ENOENT (No such file or directory)", etc. This works for any program you can run from the command-line, e.g., strace python myapp.py -e open,access... Note: the above command uses php-cli, not mod_php, which is a different SAPI with diff configs, etc. Show Sample Output


    7
    strace php tias.php -e open,access 2>&1 | grep foo.txt
    rkulla · 2010-04-20 19:42:42 6
  • List all accessed configuration files while executing a program in linux terminal (improved version)

    Last listed files presumably have higher precedency then files listed first, i.e. configuration files in the personal .config directory will be listed last and their config parameters will be more authoritative then default config parameters defined in /etc directory which are usually listed above them. If you replace ".conf" with ".ini" in the command, initial files will be listed instead of config files. If you do not like to list multiple access to the same config file, pipe to "uniq" or "uniq -c" to prefix lines by the number of occurrences Show Sample Output


    7
    strace 2>&1 <any_executable> |egrep -o "\".*\.conf\""
    knoppix5 · 2020-07-31 10:57:29 201
  • trace the system calls made by a process (and its children)

    strace can be invaluable in trying to figure out what the heck some misbehaving program is doing. There are number of useful flags to limit and control its output, and to attach to already running programs. (See also 'ltrace'.) Show Sample Output


    5
    strace -f -s 512 -v ls -l
    mkc · 2009-02-06 02:45:33 21
  • Catch a proccess from a user and strace it.

    It sits there in a loop waiting for a proccess from that user to spawn. When it does it will attach strace to it Show Sample Output


    4
    x=1; while [ $x = 1 ]; do process=`pgrep -u username`; if [ $process ]; then x=0; fi; done; strace -vvtf -s 256 -p $process
    dimentox · 2009-09-22 16:46:27 8
  • Find files that were modified by a given command

    Traces the system calls of a program. See http://linuxhelp.blogspot.com/2006/05/strace-very-powerful-troubleshooting.html for more information.


    3
    strace <name of the program>
    eitland · 2009-08-31 20:42:50 10
  • Strace all signals processes based on a name ( The processes already started... ) with bash built-in

    Especially for sysadmins when they don't want to waste time to add -p flag on the N processes of a processname. In the old school, you did ; pgrep processname and typing strace -f -p 456 -p 678 -p 974... You can add -f argument to the function. That way, the function will deal with pgrep to match the command-line. Example : processname -f jrockit


    3
    straceprocessname(){ x=( $(pgrep "$@") ); [[ ${x[@]} ]] || return 1; strace -vf ${x[@]/#/-p }; }
    sputnick · 2009-12-03 00:04:39 8
  • Terminal Escape Code Zen - Strace and Tput

    Depending on the TERM, the terminfo version, ncurses version, etc.. you may be using a varied assortment of terminal escape codes. With this command you can easily find out exactly what is going on.. This is terminal escape zen! ( 2>&2 strace -f -F -e write -s 1000 sh -c 'echo -e "initc\nis2\ncnorm\nrmso\nsgr0" | tput -S' 2>&1 ) | grep -o '"\\[^"]*"' --color=always "\33]4;%p1%d;rgb:%p2%{255}%*%{1000}%/%2.2X/%p3%{255}%*%{1000}%/%2.2X/%p4%{255}%*%{1000}%/%2.2X\33\\\33[!p\33[?3;4l\33[4l\33>\33[?12l\33[?25h\33[27m\33(B\33[m" Lets say you want to find out what you need to echo in order to get the text to blink.. echo -e "`tput blink`This will blink`tput sgr0` This wont" Now you can use this function instead of calling tput (tput is much smarter for portable code because it works differently depending on the current TERM, and tput -T anyterm works too.) to turn that echo into a much faster executing code. tput queries files, opens files, etc.. but echo is very strait and narrow. So now you can do this: echo -e "\33[5mThis will blink\33(B\33[m This wont" More at http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html Show Sample Output


    3
    termtrace(){( strace -s 1000 -e write tput $@ 2>&2 2>&1 ) | grep -o '"[^"]*"';}
    AskApache · 2010-03-17 08:53:41 7
  • intercept stdout/stderr of another process or disowned process

    Useful to recover a output(stdout and stderr) "disown"ed or "nohup"ep process of other instance of ssh. With the others options the stdout / stderr is intercepted, but only the first n chars. This way we can recover ALL text of stdout or stderr Show Sample Output


    3
    strace -e write=1,2 -p $PID 2>&1 | sed -un "/^ |/p" | sed -ue "s/^.\{9\}\(.\{50\}\).\+/\1/g" -e 's/ //g' | xxd -r -p
    glaudiston · 2010-10-06 19:37:39 4
  • easily strace all your apache processes

    Will open strace on all apache process, on systems using sbin/apache (debian) or sbin/httpd (redhat), and will follow threads newly created.


    3
    ps auxw | grep -E 'sbin/(apache|httpd)' | awk '{print"-p " $2}' | xargs strace -F
    gormux · 2016-08-04 10:59:58 14
  • Locate config files of the program

    Locate config files of the program. May not be used for interactive programs like vim.


    1
    strace -e open zim 2>&1 1>/dev/null | fgrep ~ | fgrep -v "= -1" | cut -d'"' -f2
    unixmonkey17435 · 2011-01-31 22:46:51 3
  • easily strace all your apache processes

    This version also attaches to new processes forked by the parent apache process. That way you can trace all current and *future* apache processes.


    1
    ps auxw | grep sbin/apache | awk '{print"-p " $2}' | xargs strace -f
    msealand · 2013-02-19 19:14:57 5
  • Advanced python tracing

    Trace python statement execution and syscalls invoked during that simultaneously Show Sample Output


    1
    strace python -m trace --trace myprog.py | grep -v 'write(1,'
    roolebo · 2016-05-27 21:01:01 64
  • See what apache is doing without restarting it in debug mode


    0
    pidof httpd | sed 's/ / -p /g' | xargs strace -fp
    daniele · 2011-06-28 09:53:19 3
  • change binary string readable


    0
    # strace ... | perl -lne '@F=split(/\\/, $_);for(@F){push @ddd, sprintf("%x", oct("0" . $_))}END{shift @ddd; print pack("H*", join("", @ddd));}'
    zwxajh · 2012-10-16 14:24:13 4
  • strace a program

    How to figure out what a program is doing. -tt detailed timestamps -f also strace any child processes -v be very verbose, even with common structures -o write output to file -s N capture up to N characters of strings, rather than abbreviating with ...


    0
    strace -ttvfo /tmp/logfile -s 1024 program
    ryanchapman · 2013-07-06 08:19:29 6
  • easily strace all your apache *child* processes

    On debian parent process is running as root, workers as www-data. You can run strace in backgroud, get its PID, curl your webpage, kill strace and read your stats.


    0
    strace -c $(ps -u www-data o pid= | sed 's/^/-p/')
    brablc · 2015-11-25 08:10:52 11
  • easily trace all Nginx processes

    Nginx (and other webservers like Apache) can be awkward to trace. They run as root, then switch to another user once they're ready to serve web pages. They also have a "master" process and multiple worker processes. The given command finds the process IDs of all Nginx processes, joins them together with a comma, then traces all of them at once with "sudo strace." System trace output can be overwhelming, so we only capture "networking" output. TIP: to kill this complex strace, do "sudo killall strace". Compare with a similar command: http://www.commandlinefu.com/commands/view/11918/easily-strace-all-your-apache-processes Show Sample Output


    0
    sudo strace -e trace=network -p `pidof nginx | sed -e 's/ /,/g'`
    shavenwarthog · 2016-01-28 18:48:16 12
  • strace to find out what files a process executes


    0
    strace -f -e trace=process [command]
    Raboo · 2016-07-12 12:27:56 11
  • easily strace all your apache processes


    0
    strace -p "`pidof httpd`"
    weirdan · 2016-07-28 01:34:55 13
  • Linux system calls of MySQL process


    0
    strace -c -p $(pidof -s mysqld) -f -e trace=all
    shantanuo · 2020-02-27 03:35:17 140
  • Find which config-file is read


    0
    strace 2>&1 geany |grep geany.conf
    knoppix5 · 2020-04-20 19:42:39 107

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Run a command only when load average is below a certain threshold
Good for one off jobs that you want to run at a quiet time. The default threshold is a load average of 0.8 but this can be set using atrun.

Convert spaces in file names to underscores

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

list folders containing less than 2 MB of data
This command will search all subfolders of the current directory and list the names of the folders which contain less than 2 MB of data. I use it to clean up my mp3 archive and to delete the found folders pipe the output to a textfile & run: $ while read -r line; do rm -Rv "$line"; done < textfile

Burn CD/DVD from an iso, eject disc when finished.
cdrecord -scanbus will tell you the (x,y,z) value of your cdr (for example, mine is 3,0,0)

Run a command for blocks of output of another command
The given example collects output of the tail command: Whenever a line is emitted, further lines are collected, until no more output comes for one second. This group of lines is then sent as notification to the user. You can test the example with $ logger "First group"; sleep 1; logger "Second"; logger "group"

ASCII art of yourself
Use libcaca to render ascii chars on the webcam input... or don't.

batch convert Nikon RAW (nef) images to JPG
converts RAW files from a Nikon DSLR to jpg for easy viewing etc. requires ufraw package

a function to create a box of '=' characters around a given string.
First argument: string to put a box around. Second argument: character to use for box (default is '=') Same as command #4948, but shorter, and without the utility function.

Backup all mysql databases to individual files on a remote server
It grabs all the database names granted for the $MYSQLUSER and gzip them to a remote host via SSH.

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