logging(7) logging(7)
NAME
Logging - Why, What & How We Log
Description
The npm CLI has various mechanisms for showing different levels of
information back to end-users for certain commands, configurations &
environments.
Setting Log File Location
All logs are written to a debug log, with the path to that file printed
if the execution of a command fails.
The default location of the logs directory is a directory named _logs
inside the npm cache. This can be changed with the logs-dir config
option.
For example, if you wanted to write all your logs to the current
working directory, you could run: npm install --logs-dir=.. This is
especially helpful in debugging a specific npm issue as you can run a
command multiple times with different config values and then diff all
the log files.
Log files will be removed from the logs-dir when the number of log
files exceeds logs-max, with the oldest logs being deleted first.
To turn off logs completely set --logs-max=0.
Setting Log Levels
loglevel
loglevel is a global argument/config that can be set to determine the
type of information to be displayed.
The default value of loglevel is "notice" but there are several
levels/types of logs available, including:
o "silent"
o "error"
o "warn"
o "notice"
o "http"
o "info"
o "verbose"
o "silly"
All logs pertaining to a level proceeding the current setting will be
shown.
Aliases
The log levels listed above have various corresponding aliases,
including:
o -d: --loglevel info
o --dd: --loglevel verbose
o --verbose: --loglevel verbose
o --ddd: --loglevel silly
o -q: --loglevel warn
o --quiet: --loglevel warn
o -s: --loglevel silent
o --silent: --loglevel silent
foreground-scripts
The npm CLI began hiding the output of lifecycle scripts for npm
install as of v7. Notably, this means you will not see logs/output from
packages that may be using "install scripts" to display information
back to you or from your own project's scripts defined in package.json.
If you'd like to change this behavior & log this output you can set
foreground-scripts to true.
Timing Information
The --timing config </using-npm/config#timing> can be set which does a
few things:
1. Always shows the full path to the debug log regardless of command
exit status
2. Write timing information to a process specific timing file in the
cache or logs-dir
3. Output timing information to the terminal
This file contains a timers object where the keys are an identifier for
the portion of the process being timed and the value is the number of
milliseconds it took to complete.
Sometimes it is helpful to get timing information without outputting
anything to the terminal. For example, the performance might be
affected by writing to the terminal. In this case you can use --timing
--silent which will still write the timing file, but not output
anything to the terminal while running.
Registry Response Headers
npm-notice
The npm CLI reads from & logs any npm-notice headers that are returned
from the configured registry. This mechanism can be used by third-party
registries to provide useful information when network-dependent
requests occur.
This header is not cached, and will not be logged if the request is
served from the cache.
Logs and Sensitive Information
The npm CLI makes a best effort to redact the following from terminal
output and log files:
o Passwords inside basic auth URLs
o npm tokens
However, this behavior should not be relied on to keep all possible
sensitive information redacted. If you are concerned about secrets in
your log file or terminal output, you can use --loglevel=silent and
--logs-max=0 to ensure no logs are written to your terminal or
filesystem.
See also
o npm help config
June 2023 logging(7)
npm 9.7.1 - Generated Sat Jun 10 18:41:10 CDT 2023