Linux Survival Basics
Read-only, can be slowCount Source Files by Extension
You need a small inventory of source file types.
Command
find source -type f -printf '%f\n' | sed -n 's/.*\.//p' | sort | uniq -c | sort -nrBefore you run this
System impact: Read-only. Can create load on large logs, directories, filesystems, or process tables.
When not to use it: Do not use it for extensionless files unless you adapt the command.
Expected output
File extension counts sorted from most common to least common.
System impact
Read-only, can be slow. Nothing changes. The command derives extensions from filenames and counts them.
Scope this to the smallest useful path or service on busy systems.
Recovery / rollback: no state is changed.
When to use it
Use during backup sanity checks when a content type may be missing.
When not to use it
Do not use it for extensionless files unless you adapt the command.
next steps
Related commands
Show Big Files in Human Units
Byte counts are precise. Human units are faster under pressure.
find /var -type f -printf '%s %p\n' | sort -nr | head -10 | awk '{printf "%.1f MB %s\n", $1/1024/1024, $2}'
Find the Files Eating Your Disk
The disk was full, but guessing at folders was the slow part.
find /var -type f -printf '%s %p\n' | sort -nr | head -20
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find logs/ -type f -printf '%s %p\n' | sort -nr | head -10
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find /etc/apache2/sites-enabled -maxdepth 1 -type l -printf '%f -> %l
' 2>/dev/null | sort
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Turn noisy test logs into a ranked failure list.
grep -RhoE '[A-Za-z0-9_./-]+\.(test|spec)\.(js|ts|py|rb)' logs/ | sort | uniq -c | sort -nr | head
Study mapping
Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.
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