sort -t: Set the Field Separator

sort -t tells sort which character delimits fields so -k can target a column.

Without -t, sort splits on a non-blank to blank transition. For CSV or colon data you must name the delimiter yourself.

What it does

sort -t C sets C as the single-character field separator used to locate -k keys. With -t, every separator starts a new field, so consecutive separators produce empty fields, unlike the default whitespace mode that collapses runs of blanks.

Common usage

Terminal

sort -t, -k2,2 data.csv          # sort CSV by 2nd column
sort -t: -k3,3n /etc/passwd       # numeric sort on UID
sort -t$'\t' -k1,1 data.tsv       # tab-separated

Options

Flag	What it does
-t <char>	Use <char> as the field separator
-t $'\t'	Use a literal tab as the separator
-k F1,F2	Field range the separator defines
-n / -r	Per-key modifiers attach to -k

In CI

For tab-separated data, pass -t $'\t' (ANSI-C quoting) rather than a literal tab you cannot see in the script. The default no-t mode treats runs of spaces as one separator; with -t, two spaces make an empty middle field.

Common errors in CI

sort -t " " behaves differently from the default: a literal space separator does not collapse runs, so multiple spaces create empty fields and shift your columns. Real CSV with quoted commas cannot be parsed by -t, since sort has no quoting awareness; use a CSV-aware tool for that.

Related guides

sort -k: Sort by Field or Columnsort -k sorts by a chosen field rather than the whole line. Reference for -k, -t field separators, key ranges… cut -f: Extract Columns by Fieldcut -f extracts delimited fields from each line. Reference for -f, -d, field ranges, and the tab-default and… sort -n: Numeric Sorting in CI Pipelinessort -n orders lines by numeric value instead of as strings. Reference for -n, -g, and the locale and leading… join: Relational Join on a Common Fieldjoin merges two sorted files on a shared key field, like a SQL join. Reference for -1/-2, -t, -a, and the sor…