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I'm running a DB2 stored procedure from Python using subprocess.run. The command works perfectly when I run it directly in my shell:

db2 'CALL GET_DBSIZE_INFO(?, ?, ?, 0);' | awk -F': *' '/Parameter Value/ { print $2 }'

It returns the expected value when run manually:

2025-11-25-06.20.33.191132
3702824960
56861528064

However, when I run the same command through Python:

import subprocess

con = "db2 connect to sample user **** using ****"
cmd = "db2 'CALL GET_DBSIZE_INFO(?, ?, ?, 0);' | awk -F': *' '/Parameter Value/ { print $2 }'"
res1 = subprocess.run(con, shell=True, capture_output=True, text=True)
res2 = subprocess.run(cmd, shell=True, capture_output=True, text=True)
print(res2.stdout)
print(res2.stderr)

I get inconsistent behavior:

  • sometimes stdout is an empty string ""
  • sometimes I get this error: 
    SQL1024N  A database connection does not exist.  SQLSTATE=08003

But I never get the actual output that I consistently receive when running the same command manually in the shell.

Improve this question
3
  • Db2 command shell is tricky. You cannot inherit the environment to a subprocess. Commented Nov 25 at 15:08
  • stackoverflow.com/questions/18724271/… Commented Nov 25 at 15:12
  • Both of the statements (connect, call) must run in the same subprocess for it to work correctly. You can arrange to use a single subprocess if you change the command-line to use both statements , separated by whatever character(s) your operating-system shell requires to link them (for example on unix type operating systems that is the ampersand character, while on ms-windows it is the double-ampersand). Commented Nov 26 at 10:19
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