CODEWITHSUNDEEP
c++clinuxshellunix
Topilski Alexandr
Topilski Alexandr

Reputation: 669

How can I get command line arguments passed to the running process?

In the Linux platform, if I write in console ps -p "pid" -o command I get full line with all argument which passed in terminal when I run the program. Output in console something like this: COMMAND gedit /home/sasha/Work/unloker/main.cpp (Ubuntu). Now I'm writing the program which main purpose to get complete input command line of process. My C++ code is:

snprintf(path_cmdline, sizeof(path_cmdline), "/proc/%d/cmdline", pid);
fd_cmdline = open(path_cmdline, O_RDONLY);
if (fd_cmdline < 0) {
} else {
  char process_name[PATH_MAX];
  if (read(fd_cmdline, process_name, PATH_MAX) < 0) {
  } else {
     pid_info pid_t;
     pid_t.pid=pid;
     strcpy(pid_t.command_line,process_name);
     strcpy(pid_t.process_name,basename(process_name));
     std::cout << pid_t << std::endl;
  }
}

and output of my program somthing like this: 10753 gedit gedit, but how can I get full command line as when the output of the ps -p "pid" -o command?

Where in the /proc/%d/ kept full command line of the running program? In Solaris system I know exist command pargs which do what I want, may be how now where I may found sources of this command?

Upvotes: 2

Views: 5361

Answers (2)

Jan Hudec
Jan Hudec

Reputation: 76266

The arguments in /proc/pid/cmdline is a list of strings, separated with 0 bytes. Therefore treating it as C string, which is terminated by first 0 byte, will only give you the process name. Replace all 0 bytes up to the size returned by read with spaces and try again.

Here is proof:

$ hexdump -bc < /proc/32096/cmdline
0000000 142 141 163 150 000 055 162 143 146 151 154 145 000 056 142 141
0000000   b   a   s   h  \0   -   r   c   f   i   l   e  \0   .   b   a
0000010 163 150 162 143 000
0000010   s   h   r   c  \0
0000015

Upvotes: 9

msEmmaMays
msEmmaMays

Reputation: 1063

in linux, the running process info is stored in the /proc/ folder -
/proc/{PROCESS_ID}/cmdline to be exact - for example here is chrome-

 $cat /proc/3193/cmdline 
 /opt/google/chrome/chrome --type=renderer --lang=en-US --force-fieldtrials=ConnCountImpact/conn_count_6/ConnnectBackupJobs/ConnectBackupJobsEnabled/DnsImpact/default_enabled_prefetch/GlobalSdch/global_enable_sdch/IdleSktToImpact/idle_timeout_10/OmniboxDisallowInlineHQP/Standard/OmniboxSearchSuggest/6/Prerender/ContentPrefetchPrerender1/ProxyConnectionImpact/proxy_connections_32/SBInterstitial/V2/SpdyImpact/spdy3/UMA-Dynamic-Binary-Uniformity-Trial/default/UMA-Uniformity-Trial-1-Percent/group_31/UMA-Uniformity-Trial-10-Percent/group_05/UMA-Uniformity-Trial-20-Percent/default/UMA-Uniformity-Trial-5-Percent/group_13/UMA-Uniformity-Trial-50-Percent/group_01/WarmSocketImpact/warmest_socket/ --enable-crash-reporter=81A0480CAE65B69A53CE6E791EAA05A5,Ubuntu 10.10 --disable-client-side-phishing-detection --renderer-print-preview --disable-accelerated-2d-canvas --channel=2980.13.513987986

Upvotes: 1

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